将单调元组转换为列表

Question

a=(3)
b=list(a)

typeError: 'int' object is not iterable

but

a=[3]
b=tuple(a)
c=list(b)

runs without error.

please explain this.

Answer 1

That's because (3) is just 3 . tuple s are defined by the comma, not the parentheses. If you want a tuple with one element, add a comma: (3,) .

Answer 2

(3) is the number 3 in parentheses and (3,) is a tuple:

>>> a = (3)
>>> type(a)
<type 'int'>
>>> a = (3,)
>>> type(a)
<type 'tuple'>

There are no ambiguity with [3] so it's a list:

>>> a = [3]
>>> type(a)
<type 'list'>

The list constructor accepts a tuple or a list but not a int .

Answer 3

Define tuple by using comma ,

type( (3,) ) its of type 'tuple'

type(3) its of type 'int'