Python-串列list
===
###### tags: `python`
> [name=Ice]
> [time=Fri, Oct 28, 2022 3:58 PM]
## 串列建立
### 中括號包住值
```python=
a = ['zero', 'one', 'two']
print(a) #['zero', 'one', 'two']
```
### 使用for loop輸入大量值
```python=
a = [i for i in range(0,10)]
print(a)
#[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
a = [1 for i in range(0,10)]
print(a)
#[1, 1, 1, 1, 1, 1, 1, 1, 1, 1]
```
### 拆字串轉串列 list()
```python=
a='cute'
a=list(a)
print(a) #['c', 'u', 't', 'e']
```
### 切割split()
```python=
a = 'Ice is so cute'
print(a.split(" "))
#['Ice', 'is', 'so', 'cute']
```
## List Method
### **len()** List長度
查詢list長度
```python=
a = [1, 2, 3]
print(len(a)) #3
```
### **append()** 增加元素
末端增加元素
```python=
a = ['a', 'b', 'c']
a.append('d')
print(a) #['a', 'b', 'c', 'd']
```
### **insert()** 增加元素
在指定位置加上元素（後面元素往後擠）
```python=
a = ['a', 'b', 'c']
a.insert(1,'HELLO!')
print(a) #['a', 'HELLO!', 'b', 'c']
```
這裡要再提醒！list首項位址是第０位!
### **extend()** List+List
將list加入list
```python=
a = [1, 2, 3]
b = [4, 5 ,6]
a.extend(b)
print(a) #[1, 2, 3, 4, 5, 6]
```
在python內，也可以將list+list
```python=
a = [1, 2, 3]
b = [4, 5 ,6]
c = a + b
print(c) #[1, 2, 3, 4, 5, 6]
```
### **remove()** 刪除元素
刪除指定元素
```python=
a = ['a', 'j', 'b', 'c']
a.remove('j')
print(a) #['a', 'b', 'c']
```
### **del** 刪除元素
刪除指定位址元素
```python=
a = ['a', 'j', 'b', 'c']
del a[1]
print(a) #['a', 'b', 'c']
```
刪除連續位址元素
```python=
a = ['a', 'j', 'b', 'c']
del a[1:3]
print(a) #['a', 'c']
```
刪除所有元素
```python=
a = ['a', 'j', 'b', 'c']
del a[:]
print(a) #[]
```
### **pop()** 取出並刪除元素
取出指定位址且在list中刪除
```python=
#指定位址
a = ['a', 'b', 'c', 'd' ,'e']
b = a.pop(3)
print(a) #['a', 'b', 'c', 'e']
print(b) #d
```
若不指定位址，則取出且刪除最後一項
```python=
#不指定
a = ['a', 'b', 'c', 'd' ,'e']
b = a.pop()
print(a) #['a', 'b', 'c', 'd']
print(b) #e
```
### **clear()** 清空List
清空串列
```python=
a = [1, 2, 3]
a.clear()
print(a)#[]
```
### **index()** 查詢位址
查詢元素位址
```python=
a = ['a', 'b', 'c']
print(a.index('c')) #2
```
### **count()** 計算元素數量
計算指定元素數量
```python=
a = [1, 2, 3, 2, 2, 3, 5]
print(a.count(2)) #3
print(a.count(5)) #1
```
### **sort()** 排列
- reverse=False : 小到大排列
- reverse=True : 大到小排列
```python=
a = [1, 5, 3, 6, 2, 9, 4]
a.sort(reverse=True)
print(a) #[9, 6, 5, 4, 3, 2, 1]
#字母也可以排列
b = ['a','c','d','b']
b.sort(reverse=False)
print(b) #['a', 'b', 'c', 'd']
```
### **reverse()** 反轉
反轉list
```python=
a =[1, 3, 5, 6, 7, 9]
a.reverse()
print(a) #[9, 7, 6, 5, 3, 1]
```
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