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关于python:Python-入门系列-18-Tuple-的-CURD-操作

拜访 tuple

能够应用 index 的形式对 tuple 进行拜访, 比方上面拜访 tuple 中的第二个元素。


thistuple = ("apple", "banana", "cherry")
print(thistuple[1])

PS E:\dream\markdown\python> & "C:/Program Files (x86)/Python/python.exe" e:/dream/markdown/python/app/app.py
banana

正数 index

正数索引意味着从后往前计算,比如说:-1 示意最初一项,-2 示意倒数第二项,代码如下:


thistuple = ("apple", "banana", "cherry")
print(thistuple[-1])

范畴 index

能够指定一个范畴的 start 和 end 来指定一个 tuple 的 子区间,返回值就是一个新生成的 tuple,如下代码所示:


thistuple = ("apple", "banana", "cherry", "orange", "kiwi", "melon", "mango")
print(thistuple[2:5])

PS E:\dream\markdown\python> & "C:/Program Files (x86)/Python/python.exe" e:/dream/markdown/python/app/app.py
('cherry', 'orange', 'kiwi')

正数的范畴索引

如果你想从 tuple 的尾部往前进行切割,能够指定正数的 index,如下代码所示:


thistuple = ("apple", "banana", "cherry", "orange", "kiwi", "melon", "mango")
print(thistuple[-4:-1])


PS E:\dream\markdown\python> & "C:/Program Files (x86)/Python/python.exe" e:/dream/markdown/python/app/app.py
('orange', 'kiwi', 'melon')

查看 item 是否存在

查看 tuple 中的某一项是否存在,能够应用 in 关键词。


thistuple = ("apple", "banana", "cherry")
if "apple" in thistuple:
  print("Yes,'apple'is in the fruits tuple")

更新 tuple

tuple 是不可批改的,意味着一旦 tuple 创立好之后,你不能对其进行新增,删除,批改,但也有一些变通方法。

批改 tuple 值

变通方法就是,能够先将 tuple 转成 list,而后在 list 上进行批改,最初再将 list 转成 tuple 即可,如下代码所示:


x = ("apple", "banana", "cherry")
y = list(x)
y[1] = "kiwi"
x = tuple(y)

print(x)

PS E:\dream\markdown\python> & "C:/Program Files (x86)/Python/python.exe" e:/dream/markdown/python/app/app.py
('apple', 'kiwi', 'cherry')

tuple 中新增 / 删除

同样的情理,还是应用 list 作为两头转换,实现 tuple 的 add / remove 操作,代码如下:


thistuple = ("apple", "banana", "cherry")
y = list(thistuple)
y.append("orange")
thistuple = tuple(y)
print(thistuple)

PS E:\dream\markdown\python> & "C:/Program Files (x86)/Python/python.exe" e:/dream/markdown/python/app/app.py
('apple', 'banana', 'cherry', 'orange')


thistuple = ("apple", "banana", "cherry")
y = list(thistuple)
y.remove("apple")
thistuple = tuple(y)
print(thistuple)

PS E:\dream\markdown\python> & "C:/Program Files (x86)/Python/python.exe" e:/dream/markdown/python/app/app.py
('banana', 'cherry')

肢解 tuple

当初有了一个 tuple,那如何将 tuple 中的值肢解到几个变量中呢?这就须要应用 unpacking 操作,代码如下:


fruits = ("apple", "banana", "cherry")

(green, yellow, red) = fruits

print(green)
print(yellow)
print(red)

PS E:\dream\markdown\python> & "C:/Program Files (x86)/Python/python.exe" e:/dream/markdown/python/app/app.py
apple
banana
cherry

tuple 中的 * 操作

如果须要肢解的 tuple 个数大于右边的变量个数,那么能够将一个变量申明成 *,示意将 多余的 tuple 元素作为一个汇合赋给 * 号变量,如果不明确的话,参考上面代码:


fruits = ("apple", "banana", "cherry", "strawberry", "raspberry")

(green, yellow, *red) = fruits

print(green)
print(yellow)
print(red)


PS E:\dream\markdown\python> & "C:/Program Files (x86)/Python/python.exe" e:/dream/markdown/python/app/app.py
apple
banana
['cherry', 'strawberry', 'raspberry']

同样这个 * 号变量 也能够指定任意地位,如下代码所示:


fruits = ("apple", "mango", "papaya", "pineapple", "cherry")

(green, *tropic, red) = fruits

print(green)
print(tropic)
print(red)

PS E:\dream\markdown\python> & "C:/Program Files (x86)/Python/python.exe" e:/dream/markdown/python/app/app.py
apple
['mango', 'papaya', 'pineapple']
cherry

tuple 遍历

遍历 tuple 通常有两种做法。

  • 应用 for 循环

thistuple = ("apple", "banana", "cherry")
for x in thistuple:
  print(x)
  • 应用 range() + len()

除了简略粗犷的 for 循环,还能够利用下标实现 for 操作,代码如下:


thistuple = ("apple", "banana", "cherry")
for i in range(len(thistuple)):
  print(thistuple[i])
  • 应用 while 循环

也能够通过 len() 获取 tuple 的长度,而后应用 while 循环,不过这里记得在循环的过程中,要记得将下标自增,如下代码所示:


thistuple = ("apple", "banana", "cherry")
i = 0
while i < len(thistuple):
  print(thistuple[i])
  i = i + 1

PS E:\dream\markdown\python> & "C:/Program Files (x86)/Python/python.exe" e:/dream/markdown/python/app/app.py
apple
banana
cherry

tuple 合并

合并多个 tuple 也是非常简单的,通常有二种做法。

    • 操作

能够间接在两个 tuple 中应用 + 操作,如下代码所示:


tuple1 = ("a", "b" , "c")
tuple2 = (1, 2, 3)

tuple3 = tuple1 + tuple2
print(tuple3)

PS E:\dream\markdown\python> & "C:/Program Files (x86)/Python/python.exe" e:/dream/markdown/python/app/app.py
('a', 'b', 'c', 1, 2, 3)
  • x 操作

如果想让 tuple 中内容反复呈现几次,这个几次能够应用 x num 的操作,这里的 num 就是几次的意思,如下代码所示:


fruits = ("apple", "banana", "cherry")
mytuple = fruits * 2

print(mytuple)

PS E:\dream\markdown\python> & "C:/Program Files (x86)/Python/python.exe" e:/dream/markdown/python/app/app.py
('apple', 'banana', 'cherry', 'apple', 'banana', 'cherry')

其余的 tuple 办法

除了下面介绍的几个,tuple 还有如下几个内建办法。

译文链接:https://www.w3schools.com/pyt…

更多高质量干货:参见我的 GitHub: python

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