Question

以下是我的代码的摘录！

division = ["Division","Divide","/","div"]
multiplication =["*","x","times","multiply","multiplication","multiple"]
subtraction = ["-",'minus','subtract','subtraction']
addition = ['+','plus','addition','add']
root = ['root','squareroot','square root']
square = ['square','squared','power 2']

choice = input('calculation type')
print(choice == (division or multiplication or subtraction or addition))

到目前为止，它只给出“假”。如何检查多个列表中是否存在变量？我试图在列表中创建列表，但我仍然得到“False”，这是代码......

division = ["Division","Divide","/","div"]
multiplication = ["*","x","times","multiply","multiplication","multiple"]
subtraction = ["-",'minus','subtract','subtraction']
addition = ['+','plus','addition','add']
root = ['root','squareroot','square root']
square = ['square','squared','power 2']
basic_double = [division,multiplication,subtraction,addition]
basic_single = [root,square]
choice = input('calculation type')
print(choice == basic_double or basic_single)

任何帮助将不胜感激！：D谢谢!!!

Answer 1

测试choice是否在列表的any中：

any(choice in ls for ls in [division, multiplication, subtraction, addition])

如果给定迭代的至少一个元素是真实的，则

any返回True。

choice in ls测试choice是否是列表的元素。

choice in ls for ls in [division, multiplication, subtraction, addition]是一个生成器理解，这意味着它是一个迭代器，它为choice in ls中任何可能的ls返回[division, multiplication, subtraction, addition]的结果。

如果这些列表中的一个包含choice，则any将返回True，否则返回False。

Answer 2

您可以使用itertools.chain()检查所有列表中的选项：

if choice in chain(division, multiplication, subtraction, addition):

Answer 3

现在，您将String，choice与一系列列表进行比较。当您比较两种不同的数据类型时，这将永远不会是真的。

您应该使用“in”关键字检查每个列表

if choice in division:
     #this returns true if the String set to choice is in the list of objects in division.
else if choice in multiplication:
.
.
.

此比较将帮助您在列表中找到您要查找的单词。

Answer 4

如果您想检查Choise是否在您的示例中提供的四个列表中的任何一个：

if choice in division + multiplication + subtraction + addition:
   # do something when its in any of it.
   ...

Answer 5

现在，您的代码在print函数中进行了以下比较：

choice == ["Division","Divide","/","div"] or ["*","x","times","multiply","multiplication","multiple"] or ["-",'minus','subtract','subtraction'] or ['+','plus','addition','add']

由于short-circuiting，这会减少为：

choice == ["Division","Divide","/","div"]

始终评估为False，因为choice不是列表。

我将包含[division, multiplication, subtraction, addition]的列表展平，然后测试以查看该列表中是否有choice。

flattened = [item for ls in [division, multiplication, subtraction, addition] for item in ls]

print(choice in flattened)

有关在python中展平列表列表的详细信息，请参阅此answer至此question。

如何检查多个列表中是否存在变量？

5 个答案: