---
tags: fewshot learning, awesome meta learning, papers
---

Awesome Few-Shot / Meta Learning Papers
===

[](https://github.com/sindresorhus/awesome)  [](https://hackmd.io/2e6l5BmYS2ebhE__dwOcgQ)

- 蒐集了一些相關 paper，紀錄於 [HackMD](https://hackmd.io/@johnnyasd12/B1puub-a4)，同步更新於 [GitHub](https://github.com/johnnyasd12/awesome-few-shot-meta-learning/blob/master/README.md)

# Content

[TOC]

# [My paper note: A Survey on Few-shot Learning](https://hackmd.io/_T-1A6nhQyG_LxTI2phQvw)

# Legacy Papers
- [awesome meta learning](https://github.com/floodsung/Meta-Learning-Papers)
- Distance metric learning for large margin nearest neighbor classification. JMLR 2009
- shows that non-parametric models (Weinberger & Saul, 2009) are able to capture local and heterogeneous structures in data.

## Deep transfer metric learning. CVPR 2015
- **reducing intra-class variations of features** has been highlighted in this paper (deeper backbone???)

# Metric-based Methods

## Siamese neural networks for one-shot image recognition. 2015

## FaceNet: A Unified Embedding for Face Recognition and Clustering. CVPR 2015

## Matching Networks for One Shot Learning. NIPS 2016
- [Andrej Karpathy note](https://github.com/karpathy/paper-notes/blob/master/matching_networks.md)
- [我的筆記](https://hackmd.io/s3jGbRDmSTWXmZKIg_ExHQ)
- [code (TF)](https://github.com/AntreasAntoniou/MatchingNetworks)
- [code (PyTorch)](https://github.com/BoyuanJiang/matching-networks-pytorch)
- [code (TF) - 2](https://github.com/markdtw/matching-networks)
- [code (Keras)](https://github.com/cnichkawde/MatchingNetwork)
- **第一個提出 episodic training**
- 第一個提出 **mini-ImageNet**
- we devised a new data set – **miniImageNet** – consisting of **60,000** colour images of size 84 × 84 with **100 classes, each having 600 examples**.
- attention、memory network(multi-hopping)
- 和 Siamese Network 不同的是：**Siamese Network 只學習一個 distance(或 similarity function)；而 Matching Network 直接 end-to-end 學習一個 nearest neighbor classifier**
- 使用 cosine similarity 作為 metric

## Prototypical Networks for Few-shot Learning. NIPS 2017

- [code - official (PyTorch)](https://github.com/jakesnell/prototypical-networks)
- [code - official? (PyTorch)](https://github.com/orobix/Prototypical-Networks-for-Few-shot-Learning-PyTorch)
- [code (PyTorch)](https://github.com/cyvius96/prototypical-network-pytorch)
- episodic training
- [my paper note](https://hackmd.io/Oc2fQyxCS-SdGMpu3U3QRw)
- Since there is very few data available, a classifier should have a **simple inductive bias** 這句應該是出自這篇吧

## TADAM: Task dependent adaptive metric for improved few-shot learning. NIPS 2018
- [code - official (TF)](https://github.com/ElementAI/TADAM)
- 借鑑 ProtoNet 思想
- 提出 dataset: Fewshot-CIFAR100
- metric scaling
- 學習一個 scaling factor $\alpha$，這樣可更好的輸出 metric 大小在合適的範圍
- task conditioning
- 利用 prototype 的平均值構造 task representation，然後利用 task representation 來改變 feature extractor 的 function，即具有 adaptation 的能力
- auxiliary task co-training
- 也把所有 training data 用來訓練 feature extractor，做為輔助的 task 一起 train，能讓 feature 更 generalize

## Learning to Compare: Relation Network for Few-Shot Learning. CVPR 2018
- [中文](https://zhuanlan.zhihu.com/p/35379027)
- [code - official (PyTorch fewshot)](https://github.com/floodsung/LearningToCompare_FSL)
- [code - official (PyTorch zeroshot)](https://github.com/lzrobots/LearningToCompare_ZSL)
- [code (PyTorch)](https://github.com/dragen1860/LearningToCompare-Pytorch)
- episodic training
- 將 support set 和 query 的 embedding 做 concat，然後用 NN 計算相似程度。
- 同樣的 architecture **也可以用來做 ZSL**，只要把 support set 換成 class semantic vector 即可

## Few-shot Learning with Graph Neural Networks. ICLR 2018
- metric-based [by CDFS&CloserLook]
- GNN as metric function

## Meta-learning with differentiable closed-form solvers. ICLR 2019
- ridge regression
- R2-D2
- metric-based [by CloserLook]
- 提出 dataset: CIFAR-FS

## Variational few-shot learning. ICCV 2019
- metric-based [by DAPNA]
- metric learning via variational inference

## Dense classification and implanting for few-shot learning. CVPR 2019
- metric-based [by CDFS]

## Subspace Networks for Few-shot Classification. arXiv'1905.13613

- follow "A Closer Look at Few-shot Classification" 的設定
- 根據 embedded query point 到每個 class **subspace 的距離**來 classify example

## RepMet: Representative-based metric learning for classification and few-shot object detection. CVPR 2019
- metric-based [by 2020survey]

## Infinite Mixture Prototypes for Few-shot Learning. ICML 2019 Oral
- Our infinite mixture prototypes **represent each class by a set of clusters**, unlike existing prototypical methods that represent each class by a single cluster.
- **semi-supervised and unsupervised** setting

# Optimization(Initialization)-based Methods
- learning to fine-tune?
- aim to learn a great initial parameter condition of base feature extractor, and then fine-tune the network to the unseen classes using just several examples within a few gradient steps. [by DAPNA]

## Model-Agnostic Meta-Learning for Fast Adaptation of Deep Networks. ICML 2017
- 上圖演算法 **重要**，李老師教的版本有點簡化了
- [code - official? (TF)](https://github.com/cbfinn/maml)
- [code - PyTorch](https://github.com/dragen1860/MAML-Pytorch)
- [我的 NTU lecture 筆記](https://johnnyasd12.gitbooks.io/machine-learning-ntu/content/2019-meta-learning.html)
- [中文1](https://zhuanlan.zhihu.com/p/57864886)
- [中文2](https://zhuanlan.zhihu.com/p/40417018)
- 第一次 update 參數得到 $\theta_t'$ 時，使用 support set；而真正要更新 $\theta$ 時，是使用 query set 得到的 loss
- episodic training
- 任何使用 gradient descent 的模型都適用本方法
- 尋找一個模型的 initialize parameter
- shows that simply fine-tuning a convolutional neural network on a new classification task with very few samples has been shown to provide poor results

## Meta-SGD: Learning to Learn Quickly for Few-shot Learning. arXiv'1707
- 改良 MAML (with adaptive learning rate)
- 新增 inner loop learning rate $\alpha$

## Probabilistic Model-Agnostic Meta-Learning. 2018
- dataset: Sinusoid & lines

## Gradient-based meta-learning with learned layerwise metric and subspace. ICML 2018
- initialization-based [by DAPNA]

## How to train your MAML. ICLR 2019
- MAML++
- 就是一堆 trick

## Meta-Learning with Implicit Gradients. NeurIPS 2019
- iMAML
- 大幅改動了 MAML 的架構
- 二作 Chelsea Finn 大神

## Reptile: A Scalable Meta-Learning Algorithm. 2018

## Meta-Learning with Latent Embedding Optimization. ICLR 2019
- [code - official (TF)](https://github.com/deepmind/leo)
- SOTA: LEO
- optimization-based [by CDFS]
- Hybrid: optimization-based + metric-based (RelationNet)
- 解決 MAML 不能很好的處理 high dim 的 data，即使 deeper network 也不好
- 用 (encoder+relation net) 對 data 做 latent code，然後 decode 出 w，再用 w 去算 loss 對 z 做 MAML，(**最後得到的 w' 跟 x 做 內積完 softmax??**
- OpenReview:
- contributions 有二：(1)本來 MAML 是固定 init params，現在他們把他變成低維 latent space。(2)依據 subproblem 的 input data 來決定 init params

## Learning to Stop While Learning to Predict. ICML 2020

# Black Box (Recurrent) -based Methods
- **learning an optimizer**
- equipped with an external or internal memory storage to store the transferable knowledge. [by DAPNA]

## One-shot generalization in deep generative models. JMLR 2016
- recurrent-based [by CDFS]

## Meta-learning with memory-augmented neural networks. ICML 2016
- **最早用 external memory 解 FSL classification** 的
- 別名：One-shot Learning with Memory-Augmented Neural Networks. arXiv'16
- 这篇论文解释了单样本学习与元学习的关系
- [my paper note](https://hackmd.io/OuVnw8WuT7OAuttmNtFtvg)
- Architectures with **augmented memory** capacities, such as Neural Turing Machines (NTMs), offer the ability to **quickly encode and retrieve new information**, and hence can potentially obviate the *downsides of conventional models*.
- When new data is encountered, the **conventional models must inefficiently relearn their parameters** to adequately incorporate the new information without catastrophic interference.
- We also introduce a **new method for accessing an external memory that focuses on memory content**, unlike previous methods that additionally use memory location-based focusing mechanisms.

## Optimization as a model for few-shot learning. ICLR 2017
- LSTM-based meta learning [by authors]
- include the LSTM-based meta-learner for replacing the stochastic gradient decent optimizer. [by CloserLook]

## A Simple Neural Attentive Meta-Learner. ICLR 2018
- episodic training
- RNN-based approach [by DAPNA(Few-Shot Learning as Domain Adaptation)]
- [code (PyTorch)](https://github.com/eambutu/snail-pytorch)
- [code (PyTorch) - 2](https://github.com/sagelywizard/snail)
- [code (MXNet? Gluon)](https://github.com/seujung/SNAIL-gluon)
- [my paper note (unfinished)](https://hackmd.io/rYWjR821QpWFjWPdqZzCqw)
- SOTA: SNAIL

## Meta Networks. ICML 2017
- RNN-based approach [by DAPNA]

## Memory Matching Networks for One-Shot Image Recognition. CVPR 2018

## Rapid adaptation with conditionally shifted neurons. ICML 2018
- SOTA: AdaResNet
- RNN-based [by DAPNA]

## Adaptive Posterior Learning: few-shot learning with a surprise-based memory module. ICLR 2018
- [中文](https://zhuanlan.zhihu.com/p/67388319)
- [code - official (PyTorch)](https://github.com/cogentlabs/apl)
- 只在一些 $(x^{(i)}, y^{(i)})$ 的 prediction loss 高於 threshold 時去更新 memory。因此相較於 differentiable memory(**_???_**)，計算成本降低了
- approximates probability distributions by **remembering the most surprising observations**
- algorithm can perform as well as state of the art baselines
- main contributions:
- surprise-based signal to write items to memory, **not needing to learn what to write**. So easier and faster to train, and minimizes how much data stored
- ***(不懂???) An integrated external and working memory architecture which can take advantage of the best of both worlds: scalability and sparse access provided by the working memory; and all-to-all attention and reasoning provided by a relational reasoning module.***
- A training setup which steers the system towards learning an algorithm which **approximates the posterior without backpropagating through the whole sequence of data in an episode**.
- Conclusion
- We introduced a self-contained system which can **learn to approximate a probability distribution with as little data and as quickly as it can**. This is achieved by:
- putting together the training setup which encourages adaptation
- an external memory which allows the system to recall past events
- a writing system to adapt the memory to uncertain situations
- a working memory architecture which can efficiently compare items retrieved from memory to produce new predictions
- We showed that the model can
- Reach **state of the art accuracy with a smaller memory footprint** than other meta-learning models by efficiently choosing which data points to remember.
- **Scale to very large problem sizes** thanks to the use of an external memory module **with sparse access**.
- ***(不懂???) Perform fewer than 1-shot generalization thanks to relational reasoning across neighbors.***

# Hallucination(Data Augmentation) -based Approach
- learning to **augment**

## Low-shot visual recognition by shrinking and hallucinating features. ICCV 2017

## Low-Shot Learning from Imaginary Data. CVPR 2018
- directly integrate the generator into a meta-learning algorithm for improving the classification accuracy. [by CloserLook]

## Delta-encoder: an effective sample synthesis method for few-shot object recognition. NIPS 2018
- Data method: learned transformation
- Our approach is based on a **modified auto-encoder**, denoted delta-encoder, that learns to **synthesize new samples for an unseen category just by seeing few examples** from it. The synthesized samples are then used to train a classifier.
- proposed approach learns to both **extract transferable intra-class deformations**, or "**deltas**", between same-class pairs of training examples, and to **apply those deltas** to the few provided examples of a **novel class** (unseen during training) in order to efficiently **synthesize samples from that new class**.
- the delta-encoder
- The simple key idea of this work is to **change the meaning of $E(X)$** from representing the "essence" of $X$, to representing the delta, or **"additional information" needed to reconstruct $X$ from $Y$** (an observed example from the same category).
- $E$ for encoder, $D$ for decoder

## LaSO: Label-Set Operations networks for multi-label few-shot learning. CVPR 2019

## Few-Shot Learning via Saliency-guided Hallucination of Samples. CVPR 2019

## Spot and Learn: A Maximum-Entropy Image Patch Sampler for Few-Shot Classification. CVPR 2019
- 暫時無 code (2020/4/15)

## Image Deformation Meta-Networks for One-Shot Learning. CVPR 2019
- [code - official (PyTorch)](https://github.com/tankche1/IDeMe-Net)

## Data augmentation generative adversarial networks. ICLR 2018 Workshop

# Weight Predicting -based Methods

## Hypernetworks. ICLR 2017
- generate weight approach (i think)

## Dynamic few-shot visual learning without forgetting. CVPR 2018

- SOTA
- reduce intra-class variance 的重要性

## Low-shot learning with imprinted weights. CVPR 2018

## Few-shot image recognition by predicting parameters from activations. CVPR 2018
- generate weight approach (i think)

## LGM-Net: Learning to Generate Matching Networks for Few-Shot Learning. ICML 2019

- [code - official (TF)](https://github.com/likesiwell/LGM-Net/)
- **no further tuning** steps are required compared to other meta-learning approaches

# Hybrid Methods / ???

## Meta-Learning with Differentiable Convex Optimization. CVPR 2019 (Oral)

- [code - official (PyTorch)](https://github.com/kjunelee/MetaOptNet)
- SOTA: MetaOptNet
- [few-shot 知乎](https://zhuanlan.zhihu.com/p/58298920)
- motivation：将最近邻分类器换做SVM，提高分类器的判别能力。
- 方法：提取所有图像的特征，利用SVM得到所有分类器的参数w （对偶的SVM）对测试图像进行分类，优化特征提取器参数

## Cross Attention Network for Few-shot Classification. NeurIPS 2019
- 暫時無 code (2020/4/15)
- Learn a attention(mask) to pay more attention on the part of the images

## Fine-grained visual categorization using meta-learning optimization with sample selection of auxiliary data. ECCV 2018
- done by **sharing the first several layers** of two networks to learn the generic information, while **learning a different last layer** to deal with different output for each task.

# Few-shot with Domain shift

## [最前沿：General Meta Learning](https://zhuanlan.zhihu.com/p/70782949)

## Building Computationally Efficient and Well-Generalizing Person Re-Identification. arXiv'2003
- 有做 cross-domain，但 few-shot???

## Domain-Adaptive Few-Shot Learning. arXiv'2003
- [code - official (PyTorch)](https://github.com/dingmyu/DAPN)
- 好像是跟 CloserLook 一樣的設定???
- 實驗(dataset) 跟 CloserLook 不一樣
- natural image -> cartoon-like image

## A New Benchmark for Evaluation of Cross-Domain Few-Shot Learning. arXiv'1912
- [code - official (PyTorch)](https://github.com/IBM/cdfsl-benchmark)
- train on ImageNet (miniImagenet? (perspective/natural images/color)
- performance 和 「dataset 與 imagenet 相似度」有關
- test on
- CropDisease (perspective(遠景?)/natural images/color)
- EuroSAT (no perspective/natural images/color)
- ISIC (no perspective/medical images/color)
- ChestX (no perspective/medical images/grayscale)
- cross domain 時，meta-learning 方法比 fine-tune 糟
- 可以把這篇當成一個 survey 吧

## Optimized Generic Feature Learning for Few-shot Classification across Domains. arXiv'2001
- 找 hyperparameter，怎感覺 approach 怪怪
- 而且也做 ensemble??
- train/val/test:

## Charting the Right Manifold: Manifold Mixup for Few-shot Learning. WACV 2020
- [code - official (PyTorch) from CloserLookFewShot](https://github.com/nupurkmr9/S2M2_fewshot)
- 有做 cross-domain experiments (miniImagent -> CUB)
- dataset: CIFAR-FS, CUB, miniImagenet, tieredImagenet
- 就 Manifold Mixup + Semi-supervised (+meta-learning?)
- 感覺沒什麼 novelty，而且還用 testing set 調參數?
- 感覺可以套自己的方法上去
- 是從 CloserLook 改的
- cross-domain performance 還不錯

## Revisiting Fine-tuning for Few-shot Learning. arXiv'1910, ~~ICLR 2020~~ withdrawn
- 有做 cross-domain experiments
- cross domain train/val/test:

## Few-Shot Learning as Domain Adaptation: Algorithm and Analysis. ICML 2020
- [code - official (PyTorch)【連結失效】](https://github.com/JiechaoGuan/FSL-DAPNA)
- [中文](https://www.iczhiku.com/hotspotDetail/GB2Qg4g06MgNRvRIfPzA+A==)
- 可以把 few-shot scenario 的 label shift 看成是一種 domain shift
- 建構兩個 sub-episode (沒有 class overlap) 來模擬 label(domain) shift
- 雖然主軸 few-shot 但也有做 cross-domain 實驗
- cross-domain 似乎完全 follow CloserLook 設定
- 可比較
- SOTA: DAPNA

## Few-Shot Classification on Unseen Domains by Learning Disparate Modulators. arXiv'1909, ~~ICLR 2020~~ rejected
- 怎麼感覺跟我的 idea 很像
- 別名：Domain-Agnostic Few-Shot Classification by Learning Disparate Modulators
- multi-domain dataset: Visual Decathlon
- procedure
1. 拿 source 來 train base network
2. 每個 domain 都 train 一個 per-layer module $\alpha_i$
3. 訓練一個 model selction network 來 predict 最好的 network (DoS)
- 或者直接 Averaging all network (DoA)
- 我覺得他的 DoS (在unseen domain) 的 performance 好廢，強的只有 DoA，可是 DoA 就沒 novelty，難怪沒上

## Diversity with Cooperation: Ensemble Methods for Few-Shot Classification. ICCV 2019

- 不用 meta-learning，而是用 ensemble DNN 的方式達到 SOTA 效果
- introducing new strategies to encourage the networks to cooperate, while **encouraging prediction diversity**
- **有評估 cross domain 的 performance**
- even a single network obtained by distillation yields state-of-the-art results.
- **cooperation v.s. diversity**
- 
- cooperation: encourages non-gound truth prob(紅色) to be **similar**
- diversity: encourages **orthogonality**

## A Meta-Transfer Objective for Learning to Disentangle Causal Mechanisms. 2019 (Yoshua Bengio)

- seems doing **causal inference** to fast adapt under domain shift

## Cross-Domain Few-Shot Classification. ICLR 2020
- [code - official (PyTorch)](https://github.com/hytseng0509/CrossDomainFewShot)
- **metric-based** few-shot classification often fail to generalize to unseen domains due to **large discrepancy** of the feature distribution across domains.
- core idea is to use **feature-wise transformation layers** for **augmenting the image features** using affine transforms to **simulate various feature distributions** under different domains in the **training stage**.
- further apply a **learning-to-learn approach to search for the hyper-parameters** of the **feature-wise transformation layers**.
- optimize the feature-wise transformation layers so that the model can **work well on the unseen domains** after training the **model using the seen domains**.
- modulated activations $\hat z_{c,h,w}=\gamma_c\times z_{c,h,w}+\beta_c$
- $\gamma\sim N(1,\text{softplus}(\theta_\gamma))$
- $\beta\sim N(0,\text{softplus}(\theta_\beta))$
- $\theta_\gamma,\theta_\beta$ are hyperparameters.
- single source domain experiments
- **train** on **mini-Imagenet (pseudo-seen domain???)**
- multi- source domain experiments
- miniImagenet/CUB/Cars/Places/Plantae (pseudo-unseen domain)

## Revisiting Metric Learning for Few-Shot Image Classification. arXiv'1907
- cross domain experiment, but seems not explicitly deal with domain shift in proposed method
- trained on mini-Imagenet
- tested on
- mini-Imagenet
- Caltech-101
- CUB-200
- Stanford Dogs & Cars
- Revisit triplet network, propose **K-tuplet siamese network**
- $K$ negative samples in a batch
- semi-hard mining (wats difference with facenet???)

## Label Efficient Learning of Transferable Representations across Domains and Tasks. NIPS 2017 (Li Fei-Fei)

- Our model is simultaneously optimized on **labeled source data and unlabeled or sparsely labeled data in the target domain**.
- Our method shows compelling results on **novel classes within a new domain** even when **only a few labeled examples per class** are available, outperforming the prevalent fine-tuning approach.
- initialize the CNN for the target tasks in the target domain by a **pre-trained CNN learning from source tasks** in source domain. During training, they use an **adversarial loss** calculated from **representations in multiple layers** of CNN to force the two CNNs projects samples to a **task-invariant space**.

## One Shot Domain Adaptation for Person Re-Identification. 2018

## Meta-Learning with Domain Adaptation for Few-Shot Learning under Domain Shift, ~~ICLR 2019~~ rejected
- ProtoNet + CycleGAN?
### reviewer comment at [OpenReview](https://openreview.net/forum?id=ByGOuo0cYm)
- The proposed approach consists of **combining** a known few shot learning model, prototypical nets, together with image to image translation via CycleGAN for domain adaptation. Thus the **algorithmic novelty is minor** and amounts to combining two techniques to address a different problem statement.
- though meta learning could be a solution to learn with few examples, the solution being used in this work is **not meta learning** and so should not be in the title to avoid confusion.

## Learning Embedding Adaptation for Few-Shot Learning. arXiv'1812
- [code - official (PyTorch)](https://github.com/Sha-Lab/FEAT)
- [中文](https://blog.csdn.net/xnmc2014/article/details/89925636)
- transformer + ProtoNets?
- SOTA: EA-FSL / FEAT
- 實驗也有做 cross-domain，但是也一樣，source 和 target 的 label space 相同
- 似乎沒用到 target task 的 data?
- [my paper note](https://hackmd.io/DIpAhhCjQuSErytQoTkUog)

## Domain adaption in one-shot learning. ECML-PKDD 2018

- title 的字並沒有打錯ㄛ
- 需要 target domain **unlabeled** data
- [My paper note](https://hackmd.io/VqkHvFGIToqGWsfSwLg6bA?view)
- [code - official (TF)](https://github.com/leonndong/DAOSL)
### Abstract
- given only one example of each new class. Can we **transfer knowledge learned by oneshot learning from one domain to another**?
- propose a **domain adaption framework based on adversarial networks**.
- This framework is **generalized for situations where the source and target domain have different labels**.
- use a **policy network**, inspired by human learning behaviors, to effectively **select samples from the source domain in the training process**. This sampling strategy can further improve the domain adaption performance.

## A Closer Look at Few-shot Classification. ICLR 2019

- [中文](https://zhuanlan.zhihu.com/p/64672817)
- [code - official (PyTorch)](https://github.com/wyharveychen/CloserLookFewShot)
- 提出兩個普通 baseline，發現許多情況可以和 SOTA 的 fewshot learning 媲美
- 比較的 SOTA 方法：MatchingNet、ProtoNet、RelationNet、MAML
- domain 差異小的情況下(例如CUBS)，隨著 baseNN 越強，不同 SOTA 方法的差異越小
- domain 差異大的情況下(例如miniImageNet)，隨著 baseNN 越強，不同 SOTA 方法的差異越大
- 有領域飄移情況發生時，SOTA 方法甚至沒有 baseline 表現好
- 特別強調 SOTA 在 domain adaptation 做得不好
- Reviewers' Comment
- The conclusion from the network depth experiments is that “**gaps among different methods diminish as the backbone gets deeper**”. However, in a **5-shot mini-ImageNet case, this is not what the plot shows**. Quite the opposite: the **gap increased**. Did I misunderstand something? Could you please comment on that?
- **跟我想問的問題一樣**
- Authors' Answer: Sorry for the confusion. As addressed in 4.3, gaps among different methods diminish as the backbone gets deeper *in the CUB dataset*. In the mini-ImageNet dataset, the results are more complicated due to the domain difference. We further discuss this phenomenon in Section 4.4 and 4.5. We have clarified related texts in the revised paper.

## Few-shot Learning with Meta Metric Learners. NIPS 2017 workshop on Meta-Learning, arXiv'1901.09890
- Microsoft AI & Research, IBM Research AI, JD AI Research
- Sentence Classification Services / Omniglot / Amazon Reviews
- Existing meta-learning or metric-learning based few-shot learning approaches are **limited in handling diverse domains** with various number of labels.
- we proposed a meta metric learner for few-shot learning, which is a **combination of an LSTM meta-learner and a base metric classifier**.
- The proposed method takes several advantages such as is able to **handle unbalanced classes** as well as to **generate task-specific metrics**.
- We test our approach in the ‘k-shot N-way’ few-shot learning setting used in previous work and new realistic few-shot setting with **diverse multi-domain tasks and flexible label numbers**.
- contributions
1. improve the existing few-shot learning work to **handle various class labels (not only k-shot N-way)**
2. enable the model to **learn task specific metrics** via training a meta learner
3. we are the first to investigate **few-shot deep learning methods in the text domains**.

# Understanding few-shot learning

## A Meta Understanding of Meta-Learning. ICML 2019 Workshop (under review)
- 別名 "Revisiting Meta-Learning as Supervised Learning"
- 以 supervised learning 的方式去理解 meta-learning

## Human-level concept learning through probabilistic program induction.

- (No Deep Learning, but worth reading)

## Negative Margin Matters: Understanding Margin in Few-shot Classification. arXiv'2003

## Semantic Regularization: Improve Few-shot Image Classification by Reducing Meta Shift. arXiv'1912

## A Theoretical Analysis of the Number of Shots in Few-Shot Learning. ICLR 2020

# Rethinking Meta-learning

## A Baseline for Few-Shot Image Classification. ICLR 2020

## Rethinking Few-Shot Image Classification: a Good Embedding Is All You Need? arXiv'2003
- 複雜的 meta-learning 結構其實沒這麼屌

## A Baseline for Few-Shot Image Classification. ICLR 2020

## A New Meta-Baseline for Few-Shot Learning. arXiv'2003

## All you need is a good representation: A multi-level and classifier-centric representation for few-shot learning. arXiv'1911

# Semi-supervised

## Low-shot learning with large-scale diffusion. CVPR 2018
- Data method: transform other dataset???
- semi-supervised setting to support **label propagation**
- [code - official (PyTorch, Intel MKL, faiss)](https://github.com/facebookresearch/low-shot-with-diffusion)

## Meta-Learning for Semi-Supervised Few-Shot Classification. ICLR 2018
- [code - official (TF)](https://github.com/renmengye/few-shot-ssl-public)
- 和 ProtoNet 同作者
- SOTA: Soft k-Means
- 提出 dataset: **tiered-imagenet**
- [tiered-imagenet github (非官方)](https://github.com/y2l/tiered-imagenet-tools)
- [中文(清楚)](https://blog.csdn.net/weixin_37589575/article/details/98054604)
- semi-supervised few-shot task 分兩種情況
- unlabeled support 的 class 和 labeled support 相同
- unlabeled support 的 class 和 labeled support 不同
- 这种具有误导信息的样本我们称为干扰项（distractor）
- 概念跟樓下那篇似乎有點像

## Learning to Propagate Labels: Transductive Propagation Network for Few-shot Learning. ICLR 2019
- SOTA: **TPN**
- [中文](https://blog.csdn.net/choose_c/article/details/86560074)
- [code - official (TF)](https://github.com/csyanbin/TPN)
- [code - official (PyTorch)](https://github.com/csyanbin/TPN-pytorch)
- 有點像是結合 meta-learning 跟 semi-supervised learning
- **將 support set 的 label 在 query set 中傳遞**
- [My Paper Note(unfinished)](https://hackmd.io/HlArvrYZS4S6ksipcvJtaQ)

# Combine Semantic-based Approach

## Prototype Propagation Networks (PPN) for Weakly-supervised Few-shot Learning on Category Graph. IJCAI 2019
- 應該是利用 高level 低 level 的 class 來把 prototype 做 propagation

## Learning Compositional Representations for Few-Shot Recognition. ICCV 2019
- 也用到 attribute
- CUB

## Large-Scale Few-Shot Learning: Knowledge Transfer with Class Hierarchy. CVPR 2019

## Baby steps towards few-shot learning with multiple semantics. arXiv'1906

## Generalized Zero- and Few-Shot Learning via Aligned Variational Autoencoders. CVPR 2019

- [code - official (PyTorch)](https://github.com/edgarschnfld/CADA-VAE-PyTorch)
- [Chinese1](https://travelleralone.github.io/2019-05-31/GZSLVAE/)
- [Chinese2](https://blog.csdn.net/cp_oldy/article/details/90751877)
- In this work, we take feature generation one step further and propose a model where a shared latent space of image features and class embeddings is learned by modality-specific aligned variational autoencoders.

## Adaptive Cross-Modal Few-Shot Learning, ICLR 2019 Workshop LLD, arXiv'1902
- 這篇跟我本來想到的 idea 一樣，居然有人做過了，機車
- 不過也許還沒做 domain shift?
- 對，他沒做 domain shift 哈哈哈哈
- Reviewer Comment
- this paper is **not really doing few-shot learning**, because according to section 3.2. and the experiments, the authors use the test labels in order to know which word embeddings to assign to each sample: "[...] containing label embeddings of all categories in D_train ∪ D_test". In other words, the authors use the labels (which are the goal of the classification task) to find the match between the two input modalities (to know what Glove vector to assign to each image).
- the experiments compare the results only between this multimodal approach and visual approaches. I believe using the Glove embeddings alone (no visual input) could give very good results on their own, and it is thus crucial for the authors to compare with this scenario too.
- the explanation for why you chose this form for lambda_c is unclear: "A very structured semantic space is a good choice for conditioning."

## Semantic Feature Augmentation in Few-shot Learning. ECCV 2018

- [few-shot 知乎](https://zhuanlan.zhihu.com/p/58298920)
- motivation：在特征上做数据增广不足以考察类内的变化-->在语义空间上做数据增广。
- 方法：
1. 提取类别的语义空间（人工标注的语义属性空间；word2vec得到的语义word空间）
2. 联合训练一个特征提取器和视觉特征空间到语义空间的映射。
3. 对于测试的训练图像，将其映射到语义空间，在语义空间做数据增广（加入高斯噪声或者映射到相应的相似的类别），再映射到语义空间，得到增广后的特征。
4. 将增广的特征和原有的特征联合训练一个分类器。

## Few-Shot Learning with Global Class Representations. ICCV 2019
- utilize semantic information [by DAPNA]

# others

## TAFE-Net: Task-Aware Feature Embeddings for Low Shot Learning. 2019
- metric-based [by 2020survey]

## Incremental Few-Shot Learning with Attention Attractor Networks. NIPS 2019

- problem
- This paper addresses this problem, **incremental few-shot learning**, where a regular classification network has already been trained to **recognize a set of base classes**, and several extra **novel classes** are being considered, each with only a **few labeled** examples. **After learning the novel classes**, the model is then evaluated on the overall classification performance on **both base and novel classes**

## Multi-attention Network for One Shot Learning. CVPR 2017

### [few-shot 知乎](https://zhuanlan.zhihu.com/p/58298920)

- motivation：对于一个novel类只给了一个样本，但是给定的图像可能含有其他无关的信息，因此利用一个注意力机制，只关注样本中于目标类别相关的区域。
- 方法：
1. 利用word2vec提取类别的语义信息a，CNN提取图像的视觉信息x。
2. 类似self-attention机制，以a作为query，x作为gallery和value，生成多个attention map
3. 根据生成的attention map对图像特征加权求和，得到图像的最后特征
4. 在训练集上对图像特征分类，训练整个网络
5. 测试时，输入一张训练图像和类别得到相应的特征，对测试图像，分别输入多个类别的语义信息，得到多个图像特征，最近邻比对

## Few-Shot Learning with Embedded Class Models and Shot-Free Meta Training. arXiv'1905
- **any-way, any-shot**

## NPRF: A Neural Pseudo Relevance Feedback Framework for Ad-hoc Information Retrieval. EMNLP 2018
- [code - official (TF+Keras)](https://github.com/ucasir/NPRF)
- support set 跟 query set 都跟 training set 的 data 算 KL-divergence，然後看 query set 跟 support set 的哪個 data 最像

## Meta-learning autoencoders for few-shot prediction. arXiv'1807 (MIT)

## Learning Classifiers for Target Domain with Limited or No Labels. ICML 2019
- 好像不是做 domain shift 的 @@
- 分別對 few-shot learning, generalized zero-shot learning, domain adaptation 做了實驗
- Abstract
- We propose a novel visual attribute encoding method that encodes each image as a **low-dimensional probability vector** composed of **prototypical part-type probabilities**.
- At **test-time** we **freeze the encoder and only learn/adapt the classifier** component to limited annotated labels in FSL; new semantic attributes in ZSL.

## Meta-Learning Probabilistic Inference for Prediction. ICLR 2019
- [code - official (TF)](https://github.com/Gordonjo/versa)

## Meta-Learning For Stochastic Gradient MCMC. ICLR 2019

## Unsupervised Learning via Meta-Learning. ICLR 2019

# CVPR 2019

## LCC: Learning to Customize and Combine Neural Networks for Few-Shot Learning. CVPR 2019

### [CVPR19-Few-shot - 知乎](https://zhuanlan.zhihu.com/p/67402889)

- motivation：超参数设置十分重要，利用meta-learning对每一层学习一个超参数；一个learner通常不稳定，在MAML的机制上学习如何融合多个learner。

## Meta-Transfer Learning for Few-Shot Learning. CVPR 2019
- [code - reproduced (TF)](https://github.com/y2l/meta-transfer-learning-tensorflow)
- code - reproduced (PyTorch): under-developed
- [中文](https://zhuanlan.zhihu.com/p/57134284) (僅佔小部份篇幅)
- [作者blog](https://blog.yyliu.net/meta-transfer-learning/)
- 方法 (**改良 MAML**)
1. 用 training set 所有 sample 訓練一個 NN 來 classify，得到一個 feature extractor
2. sample 多個 task，用 MAML 根據 support set 更新 classifier(最後一層?) 參數，再利用 query set 計算 gradient，微調 initial parameter
- **Hard Task(HT) meta-batch**
- 故意選一些 fail 的 task 並重組那些 data 成為 harder tasks 以用來 adverse re-training，希望 meta-learner 能在困難中成長 0.0

## Revisiting Local Descriptor based Image-to-Class Measure for Few-shot Learning. CVPR 2019
- [code - official (PyTorch)](https://github.com/WenbinLee/DN4)
- [few-shot 知乎](https://zhuanlan.zhihu.com/p/58298920)
- motivation: 全局特征对于小样本数据不是很友好，考虑局部特征，会过滤掉干扰物体以及背景的信息。
- 做法：对于query图像的每个局部特征都计算一个与support set图像的相似性

## Adversarial Meta-Adaptation Network for Blending-target Domain Adaptation. CVPR 2019
- 提出了新的 scenario: Blending-target Domain Adaptation (**BTDA**)
- 提出了 Adversarial Meta-Adaptation Network (**AMEAN**)

## Instance-Level Meta Normalization. CVPR 2019

## Task Agnostic Meta-Learning for Few-Shot Learning. CVPR 2019
- [作者導讀 中文](https://zhuanlan.zhihu.com/p/37076777)
- 直接最大化初始模型在不同类别上的熵（Entropy Maximization）来实现对任务的无偏性
- optimized-based meta-learning

### 想讀

## AutoAugment: Learning Augmentation Strategies from Data. CVPR 2019

## Divide and Conquer the Embedding Space for Metric Learning. CVPR 2019

## Finding Task-Relevant Features for Few-Shot Learning by Category Traversal. CVPR 2019
- 引用 closerlook
- 根據 support set 得到一個 channel attention，對所有的 image 做 channel attention
- [few-shot 知乎](https://zhuanlan.zhihu.com/p/58298920)
- motivation：对于few-shot的support set，现有的方法都是单独为其提取特征，没有考虑这个task的更具有判别性的特征。利用support set的所有图像的信息，提取具有判别性的特征。
- 方法：对support set生成一个channel attention。

## Learning from Adversarial Features for Few-Shot Classification. 2019

### [few-shot 知乎](https://zhuanlan.zhihu.com/p/58298920)

- motivation: 分类的交叉熵loss只会关注最显著的区域，会造成提取特征的严重过拟合。通过约束模型更加关注其他区域的特征，提高特征提取器的泛化能力。
- 方法：
1. 输入图像，经过特征提取器得到特征F，经过分类器，得到概率分布，以及entropy loss $l$
2. 求的entropy loss对输入特征F的梯度，在初始的M上加上其梯度（新得到M使entropy loss更大）。
3. 将新得到的M与输入特征F相乘，求平均，经过分类器，得到cross entropy loss $l_1$
4. 将F再经过多个卷积层，使其空间维度为1，经过分类器，得到cross entropy loss $l_2$
5. 通过 $l_1+l_2$ 优化网络

## Few-Shot Learning with Localization in Realistic Settings. CVPR 2019

## Few Shot Adaptive Faster R-CNN. CVPR 2019

## SPNet: Semantic Projection Network for Zero-Label and Few-Label Semantic Segmentation. CVPR 2019

## Dense Classification and Implanting for Few-shot Learning. CVPR 2019

## Coloring With Limited Data: Few-Shot Colorization via Memory Augmented Networks. CVPR 2019

## Variational Prototyping-Encoder: One-Shot Learning with Prototypical Images. CVPR 2019
- [code - official (PyTorch)](https://github.com/mibastro/VPE)
-

# ICML 2019

## TapNet: Neural Network Augmented with Task-Adaptive Projection for Few-Shot Learning. ICML 2019
- [code - official (Chainer)](https://github.com/istarjun/TapNet)
- 不是 domain shift
- episodic training
- learn a network & a set of per-class reference vectors
- linearly projected features as task-specific conditioning
- evaluation dataset: omniglot, miniImagenet, tieredImagenet
- test under various few-shot scenarios

## Fast Context Adaptation via Meta-Learning. ICML 2019

- We propose **CAVIA** for meta-learning, a simple extension to **MAML** that is **less prone to meta-overfitting**, easier to parallelise, and more **interpretable**.
- CAVIA partitions the model parameters into two parts: **context parameters** that serve as **additional input** to the model and are **adapted on individual tasks**, and **shared parameters** that are meta-trained and **shared across tasks**. At **test time, only the context parameters are updated**, leading to a low-dimensional task representation.

# ICCV 2019

## Deep Meta Metric Learning. ICCV 2019

- [code - official (PyTorch)](https://github.com/CHENGY12/DMML)

## Bidirectional One-Shot Unsupervised Domain Mapping. ICCV 2019

## One Shot Domain Adaptation for Person Re-Identification. ICCV 2019 Oral

- renamed to: **Self-similarity Grouping: A Simple Unsupervised Cross Domain Adaptation Approach for Person Re-identification** ?
- [code - official (PyTorch)](https://github.com/OasisYang/SSG)

## Few-shot Object Detection via Feature Reweighting. ICCV 2019

## Few-shot Unsupervised Image-to-Image Translation. ICCV 2019

## Learning Compositional Representations for Few-Shot Recognition. ICCV 2019

## Boosting Few-Shot Visual Learning with Self-Supervision. ICCV 2019

## Deep Meta Learning for Real-Time Target-Aware Visual Tracking. ICCV 2019

## Task2Vec: Task Embedding for Meta-Learning. ICCV 2019

## Meta-Sim Learning to Generate Synthetic Datasets. ICCV 2019 Oral

## Meta-Learning to Detect Rare Objects. ICCV 2019

# ECCV 2018

# AAAI 2019

## Hybrid Attention-Based Prototypical Networks for Noisy Few-Shot Relation Classification. AAAI 2019
- [code - official (PyTorch)](https://github.com/thunlp/HATT-Proto)
- aims to deal with **noisy data**

# ~~CVPR 2019 Workshop~~

# NIPS 2019 Workshop

# ICCV 2019 Workshop

# ECCV 2018 Workshop

# ICLR 2019 Workshop LLD

# [ICML 2018 Workshop](https://sites.google.com/site/icml18limitedlabels/accepted-papers)

# Unsupervised Meta-learning

## Learning Unsupervised Learning Rules. ICLR 2019 (Oral?)

## Unsupervised Learning via Meta-Learning. ICLR 2019

---
## Edge-Labeling Graph Neural Network for Few-shot Learning. arXiv'1905

# not interested currently

## Online Learning of a Memory for Learning Rates. ICRA 2018

## Learning to Learn How to Learn: Self-Adaptive Visual Navigation using Meta-Learning. CVPR 2019
- [code - official (PyTorch)](https://github.com/allenai/savn)
- 用 meta-learning 來學 Visual Navigation task

## One-Shot Unsupervised Cross Domain Translation. NeurIPS 2018
- few-shot + GAN
- They learn **separate embedding for source and target tasks in different domains** to map them into a task-invariant space, then learn a **shared classifier** to classify samples from all tasks.

## Taming MAML: Efficient unbiased meta-reinforcement learning. ICML 2019

## Efficient Off-Policy Meta-Reinforcement Learning via Probabilistic Context Variables. ICML 2019

## Sever: A Robust Meta-Algorithm for Stochastic Optimization. ICML 2019

## Probable Guarantees for Gradient-Based Meta-Learning. ICML 2019

## Meta-Learning Neural Bloom Filters. ICML 2019
- We propose a novel **memory** architecture, the **Neural Bloom Filter**, which is able to achieve significant **compression gains** over classical Bloom Filters and existing memory-augmented neural networks

## Hierarchically Structured Meta-learning. ICML 2019
- focus on **gradient-based meta-learning**

## Online Meta-Learning. ICML 2019
- MAML 作者

## Few-Shot Regression via Learned Basis Functions

- propose a few-shot learning model that is tailored specifically for **regression** tasks

## CANet: Class-Agnostic Segmentation Networks with Iterative Refinement and Attentive Few-Shot Learning. arXiv'1903

# 2020 papers

## Memory-Augmented Relation Network for Few-Shot Learning. arXiv'2005

## Augmented Bi-path Network for Few-shot Learning. arXiv'2007

## Learning from Few Samples: A Survey. arXiv'2007

## Few-shot Learning with Multi-scale Self-supervision. arXiv'2001

# Awesome Authors
- [Han-Jia Ye](https://scholar.google.com/citations?hl=zh-TW&user=mgOYhtoAAAAJ&view_op=list_works&sortby=pubdate)
- metric learning
- meta learning
* [Chelsea Finn](http://people.eecs.berkeley.edu/~cbfinn/), _UC Berkeley_
* MAML
* [Pieter Abbeel](https://people.eecs.berkeley.edu/~pabbeel/), _UC Berkeley_
* [Erin Grant](https://people.eecs.berkeley.edu/~eringrant/), _UC Berkeley_
* [Raia Hadsell](http://raiahadsell.com/index.html), _DeepMind_
* [Misha Denil](http://mdenil.com/), _DeepMind_
* [Adam Santoro](https://scholar.google.com/citations?hl=en&user=evIkDWoAAAAJ&view_op=list_works&sortby=pubdate), _DeepMind_
* [Sachin Ravi](http://www.cs.princeton.edu/~sachinr/), _Princeton University_
* [David Abel](https://david-abel.github.io/), _Brown University_
* [Brenden Lake](https://cims.nyu.edu/~brenden/), _Facebook AI Research_fjdslfjsl

# Datasets

- [TorchMeta (Library)](https://pypi.org/project/torchmeta/), [[GitHub]](https://github.com/tristandeleu/pytorch-meta)
- omniglot, mini-Imagenet
- tiered-Imagenet
- CIFAR-FS
- Fewshot-CIFAR100
- Caltech-UCSD Birds (CUBS 200)
- [Double MNIST (Multi-Digit MNIST)](https://github.com/shaohua0116/MultiDigitMNIST)
- [Triple MNIST (Multi-Digit MNIST)](https://github.com/shaohua0116/MultiDigitMNIST)
- Toy Datasets (Few-Shot Regression)
- Sine waves
- Model-Agnostic Meta-Learning for Fast Adaptation of Deep Networks. 2017
- Harmonic functions
- Uncertainty in Multitask Transfer Learning. 2018
- Sinusoid & lines
- Probabilistic Model-Agnostic Meta-Learning. 2018
- [Meta-Dataset](https://github.com/google-research/meta-dataset)
- [Few-Shot Object Detection Dataset](https://github.com/fanq15/Few-Shot-Object-Detection-Dataset)
- VPE
- traffic sign datasets
- GTSRB
- TT100K
- logo datasets
- BelgaLogos
- FlickrLogos-32
- TopLogos-10

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