Code
Country = ["China",'USA',"UK","France","German","Japan"]
print(Country)['China', 'USA', 'UK', 'France', 'German', 'Japan']3 列表
在Python中，用方括号[] 表示列表，用逗号分隔其中的元素。
3.1 访问元素
索引从0开始，而不是从1开始。
Code
print(Country[0])
print(Country[4])China
German也可以从倒数第一个数向前访问
Code
print(Country[-1])
print(Country[-2])
print(Country[-3])Japan
German
France使用列表中的值
Code
intro = f"Hello,I'm from {Country[0]}!"
print(intro)Hello,I'm from China!3.2 修改、添加和删除元素
3.2.1 修改元素
Code
num = [1,2,3,4,5,6,7,8,9]
print(num)
num[0] = 0
print(num)[1, 2, 3, 4, 5, 6, 7, 8, 9]
[0, 2, 3, 4, 5, 6, 7, 8, 9]3.2.2 添加元素
在列表末尾添加元素
追加（
append()）到列表末尾Code
num = [1,2,3,4,5,6,7,8,9] print(num) num.append(10) print(num)[1, 2, 3, 4, 5, 6, 7, 8, 9] [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]可以先创建空列表，再用
append逐个添加元素。Code
fruit = [] fruit.append("apple") fruit.append("pear") print(fruit)['apple', 'pear']在列表中插入元素
使用
insert()方法可在列表的任意位置添加元素Code
num = [1,2,3,4,5,6,7,8,9] print(num) num.insert(0,0) num[1, 2, 3, 4, 5, 6, 7, 8, 9][0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
3.2.3 删除元素
使用del 语句删除元素
Code
num = [1,2,3,4,5,6,7,8,9] del num[0] del num[2] num[2, 3, 5, 6, 7, 8, 9]使用pop()方法删除元素
弹出
pop()方法删除列表末尾的元素Code
num = [1,2,3,4,5,6,7,8,9] popped_num = num.pop() num popped_num9删除任意位置的元素
也可以使用
pop()方法删除列表中任意位置的元素，指定索引即可Code
num = [1,2,3,4,5,6,7,8,9] fifth_num = num.pop(4) num[1, 2, 3, 4, 6, 7, 8, 9]根据值删除元素
Code
num = [1,2,3,4,5,6,7,8,9] hate_num = 4 num.remove(hate_num) num[1, 2, 3, 5, 6, 7, 8, 9]
3.3 管理列表
使用
sort()方法永久排序Code
### 字母顺序 letters = ["a","r","k","n","v","z"] letters.sort() print(letters) ### 字母逆序 letters = ["a","r","k","n","v","z"] letters.sort(reverse = True) print(letters)['a', 'k', 'n', 'r', 'v', 'z'] ['z', 'v', 'r', 'n', 'k', 'a']使用
sorted()函数临时排序Code
letters = ["a","r","k","n","v","z"] sorted(letters) sorted(letters,reverse = True) print(letters)['a', 'r', 'k', 'n', 'v', 'z']使用
reverse()方法反向打印列表Code
letters = ["a","r","k","n","v","z"] letters.reverse() print(letters) #反向打印 letters.reverse() print(letters) #恢复['z', 'v', 'n', 'k', 'r', 'a'] ['a', 'r', 'k', 'n', 'v', 'z']使用
len()函数确定列表长度Code
letters = ["a","r","k","n","v","z"] len(letters)6
3.4 遍历整个列表
for循环
注意避免缩进错误，如忘记缩进、忘记缩进额外的代码行、不必要的缩进、循环后不必要的缩进、遗漏冒号、
Code
subjects = ["Chinese","Mathematics","English","Physics","Chemistry","Biology"]
for subject in subjects:
print(f"{subject}:")
print(f"{subject} is very important for students.\n")
print("day day up!")Chinese:
Chinese is very important for students.
Mathematics:
Mathematics is very important for students.
English:
English is very important for students.
Physics:
Physics is very important for students.
Chemistry:
Chemistry is very important for students.
Biology:
Biology is very important for students.
day day up!3.5 创建数值列表
3.5.1 使用range()函数创建列表
Code
for value in range(-3,3):
print(value)-3
-2
-1
0
1
2Code
numbers = list(range(-5,5,2))
numbers
squares = []
for value in range(1,11):
square=value**2
squares.append(square)
print(squares)[1, 4, 9, 16, 25, 36, 49, 64, 81, 100]3.5.2 统计函数
Code
digits = list(range(0,10))
min(digits)
max(digits)
sum(digits)453.5.3 列表推导式list comprehension
Code
squares = [i**2 for i in range(1,10)]
squares[1, 4, 9, 16, 25, 36, 49, 64, 81]3.6 slice
列表的部分称为slice。
Code
letters = ["a","r","k","n","v","z"]
# 左包含，右不包含
letters[0:3]
letters[3:5]
letters[:3] # 0，1，2
letters[:-2] # 从头到倒数第2之前1位
letters[2:] # 从第3到末尾
letters[-3:] # 从倒数第3到末尾
letters[::2] # 从头到尾每间隔2打印
letters[1::3]
# 遍历slice
for i in letters[:3]:
i.upper()
# 复制slice
字母 = letters[:] # 从头到尾
字母.append("X")
字母
letters.append("Y")
letters
#不使用slice
letters = ["a","r","k","n","v","z"]
letters
LETTERS = letters # 两种指向同一个列表
LETTERS.append("X")
LETTERS
letters
letters.append("Y")
LETTERS
letters['a', 'r', 'k', 'n', 'v', 'z', 'X', 'Y']3.7 元组tuple
Python将不能修改的值称为不可变的。而不可变的列表称为元组（tuple）。元组使用圆括号()+逗号,标识。严格地说，元组是用逗号标识的，圆括号只是让元组看起来更整洁、更清晰，并不是必须的。
Code
dimensions = (200,50,4)
dimensions
# dimensions[0] = 333 # 'tuple' object does not support item assignment
single = 9,
# single[0] = 3虽然元组的元素不能修改，但可以重新给表示元组的变量赋值
Code
dimensions = (200,50,4)
dimensions
dimensions = 2,3,4,5
dimensions
for i in dimensions:
i