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###### tags: `資訊之芽`
---
# 1st Stage Review
資芽北區2023 講師: 洪郁凱Kain
---
## Outline
- Review Syntax
- What's next?
---
## Review Syntax
練習用python內建的manual整理自己的重點
`help(...)`
----
## Review Syntax
```
basic
if--else
list
string
while
for
dictionary
function
import
```
----
## Review Syntax
basic 加減乘除
```python
# Between int/float/complex
# + - * ** / // %
# __add__, __sub__,...
print(1 + 1, 2 - 1.0, 3 * 3, 4+5j / 3)
print(1.2e3 // 3, 5**4, 3%2)
# +=, -=, *=, /=
a = 5
print(a)
a += 3
print(a)
```
----
## Review Syntax
basic 輸入
```python
str_a = input() # 字串
a, b = str_a[:2], str_a[2:] #切下前兩個字分給a，剩下分給b
num = int(input()) # 單個數字
num = eval(input()) # 單個數字(可輸入:7.0,1+5j...)
strs_a = input().split(" ") # 用" "分隔的多個字 以list裝
n, m = map(int, input().split()) # 兩個數字
nums = list(map(int, input().split())) # 多個數字 以list裝
```
----
## Review Syntax
basic 輸出
```python
print(1, 2, 3,sep=', ',end=".") # "1, 2, 3."
num = 12
print(f"{num}\t{num*10}\t{num*100}") # 用Tab對齊
print(" "*(5-len(str(num)))+str(num)) # " 12" 向右靠齊 長度為5
print(str(num).rjust(5)) # " 12" 向右靠齊 長度為5
print(f"{num:05}") # "00012" 補0 長度為5
print(str(num).center(5)) # " 12 " 置中 長度為5
```
<!-- .element: class="wrap-code" -->
----
## Review Syntax
basic 輸出
```python
a=17
print(bin(a), oct(a), hex(a)) # 0b10001 0o21 0x11
print(bin(a)[2:], oct(a)[2:], hex(a)[2:]) # 10001 21 11
```
---
## Review Syntax
if-elif-else
```python=
a = int(input())
if a%3 == 0:
print("三的倍數")
elif a%3 == 1:
print("減一後是三的倍數")
else: # 不用條件
print("減二後是三的倍數")
```
----
## Review Syntax
Boolean
```python
# Between int/float
print(1.5>0,1<0,1==0)
# Between strings lists /sets
print("aa">"ab","ba">"abbbbb")
# logic: and, or, not, (xor)
print(3>2 and 3<2, 3>2 or 3<2, not 3<2)
```
---
## Review Syntax
while
(Collatz conjecture)
```python
a = 17
while a>1:
print(a)
if a % 2:
a = 3*a + 1
else:
a = a // 2
if a == 928:
print("講師的生日！")
break # 跳出loop
# continue
```
---
## Review Syntax
for
(讓程式跳舞)
```python
for i in range(1,10):
if i == 5:
continue
print(i)
```
---
## Review Syntax
list
```python
list_a = [1,4.2,3+4j,"5",lambda x:x%3] # 可以裝幾乎所有東東
print(list("Baby Shark")) # ['B', 'a', 'b', 'y',...
print(["Baby Shark"]) # ['Baby Shark']
print(list_a[2:4]) # slice 取index = 2~3的部分
print(list_a[0]) # 取值 從0開始
print(list_a[4](list_a[1])) # 取值 結合 lambda function
list_b = [1,5,2,4,3]
print(sorted(list_b)) # 會回傳排好的list 但不會更改本來的list
list_b.sort(key=list_a[-1]) # key指定排序規則 list可用-1來取值 sort會將本來的list改變 print會噴None
print(list_b)
```
----
## Review Syntax
list 增刪修
```python
# 增
list_a = [i*10 for i in range(3)] # [0, 10, 20]
list_a.append(30) # [0, 10, 20, 30]
list_a.extend([i*10 for i in range(3,6)]) # [0, 10, 20, 30, 30, 40, 50]
# 刪除
list_a.pop(1) # [0, 20, 30, 30, 40, 50]
list_a.remove(30) # [0, 20, 30, 40, 50]
del list_a[3:] # [0, 20, 30]
# 修
list_a[0] = sum(list_a) # [50, 20, 30]
```
----
## Review Syntax
list(多維度)
```python
list_c = [[i*3 for i in range(1,j)] for j in range(10,2,-2)]
print(list_c[2][1])
print(sorted(list_c, key=lambda x:x[-1]%5, reverse=True)) # 根據元素[-1]來排列元素 由大到小
list_d = list(range(1,10,3)) # 另一個生大list的方法
sorted(list_c, key=lambda x:len(x))# 根據元素的長度（元素數量）排序 由小到大
```
<!-- .element: class="wrap-code" -->
----
## Review Syntax
list + for
```python
list_d = [[[i*3 for i in range(1,j)] for j in range(10,k,-2)] for k in range(2,5)]
for i in list_d:
for j in i:
print(j)
for k in j:
print(k)
```
---
## Review Syntax
string
```python
print("Kain"+","+"the student")
print("Kain"*3)
print(("Kain"*2)[2:5]) # 取值的運算子比乘法優先
print(','.join(["a","b","c"])) # 用join把字串黏起來
print(" Kain ".strip()) # 去掉前後空白
```
----
## Review Syntax
string
之前的[練習](https://hackmd.io/@s3131212/rkZYT74lh#/11/2)
```python
lyrics = """Never gonna give you up
Never gonna let you down
Never gonna run around and desert you
"""
positions = []
start = 0
value = "gonna"
while True:
ret = lyrics.find(value, start)
if ret == -1:
break
positions.append(ret)
start = ret + len(value)
print(positions)
```
----
## Review Syntax
string
太多了真的列不完...
```python
help(str)
```
---
## Review Syntax
dictionary
```python
d = {1:2, 3.0:4, '5':6+7j} # {key: value...}
print(len(d)) # Key-Value pairs/元素數量 亦可用在list/str
print(d[1], d['3']) # 取值
print(d.get("Dior","不存在！")) # 避免取到不存在的Key
# 檢查 key / combo skill
if 3 in d:
print(d[3])
# 增/刪/修
d[8] = "nine"
del d[1]
d.pop(8)
d['5'] = 1011
```
----
## Review Syntax
dictionary
遍歷
```python
for k, v in d.items():
print("key = {}, value = {}".format(k,v)) # format string
```
---
## Review Syntax
function
```python
def func_a(a,b,c,/,d,*,e = 3): # 預設值從後向前
print(a,b,c,d,e)
return a,c,e,b,e # return自動包成tuple
func_a(10,20,30,40,e=50)
func_a(10,20,30,e=40,d=50)
func_a(*[10*i for i in range(4)]) # 用list餵參數
func_a(*[10*i for i in range(3)],**{"d":123,"e":456}) # list-> args, dict-> kwargs
```
---
## Review Syntax
import
```python
import math
import numpy as np
from random import randint
print(math.sin(math.pi/6))
print(np.array([1,2,3]))
print(randint(5,10))
```
---
## What's next?
Debug 的萬用工具
----
## What's next?
基本語法完成之後，可在第二階段學習不同套件，達成更多運用
---
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