How to convert a set to a list in python?
Question:
I am trying to convert a set to a list in Python 2.6. I’m using this syntax:
first_list = [1,2,3,4]
my_set=set(first_list)
my_list = list(my_set)
However, I get the following stack trace:
Traceback (most recent call last):
File "<console>", line 1, in <module>
TypeError: 'set' object is not callable
How can I fix this?
Answers:
It is already a list:
>>> type(my_set)
<class 'list'>
Do you want something like:
>>> my_set = set([1, 2, 3, 4])
>>> my_list = list(my_set)
>>> print(my_list)
[1, 2, 3, 4]
EDIT:
Output of your last comment:
>>> my_list = [1,2,3,4]
>>> my_set = set(my_list)
>>> my_new_list = list(my_set)
>>> print(my_new_list)
[1, 2, 3, 4]
I’m wondering if you did something like this:
>>> set = set()
>>> set([1, 2])
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: 'set' object is not callable
I’m not sure that you’re creating a set with this ([1, 2]) syntax, rather a list. To create a set, you should use set([1, 2]).
These brackets are just envelopping your expression, as if you would have written:
if (condition1
and condition2 == 3):
print something
There’re not really ignored, but do nothing to your expression.
Note: (something, something_else) will create a tuple (but still no list).
Review your first line. Your stack trace is clearly not from the code you’ve pasted here, so I don’t know precisely what you’ve done.
>>> my_set=([1,2,3,4])
>>> my_set
[1, 2, 3, 4]
>>> type(my_set)
<type 'list'>
>>> list(my_set)
[1, 2, 3, 4]
>>> type(_)
<type 'list'>
What you wanted was set([1, 2, 3, 4]).
>>> my_set = set([1, 2, 3, 4])
>>> my_set
set([1, 2, 3, 4])
>>> type(my_set)
<type 'set'>
>>> list(my_set)
[1, 2, 3, 4]
>>> type(_)
<type 'list'>
The “not callable” exception means you were doing something like set()() – attempting to call a set instance.
[EDITED]
It’s seems you earlier have redefined “list”, using it as a variable name, like this:
list = set([1,2,3,4]) # oops
#...
first_list = [1,2,3,4]
my_set=set(first_list)
my_list = list(my_set)
And you’l get
Traceback (most recent call last):
File "<console>", line 1, in <module>
TypeError: 'set' object is not callable
Python is a dynamically typed language, which means that you cannot define the type of the variable as you do in C or C++:
type variable = value
or
type variable(value)
In Python, you use coercing if you change types, or the init functions (constructors) of the types to declare a variable of a type:
my_set = set([1,2,3])
type my_set
will give you <type 'set'> for an answer.
If you have a list, do this:
my_list = [1,2,3]
my_set = set(my_list)
Hmmm I bet that in some previous lines you have something like:
list = set(something)
Am I wrong ?
Instead of:
first_list = [1,2,3,4]
my_set=set(first_list)
my_list = list(my_set)
Why not shortcut the process:
my_list = list(set([1,2,3,4])
This will remove the dupes from you list and return a list back to you.
Whenever you are stuck in such type of problems, try to find the datatype of the element you want to convert first by using :
type(my_set)
Then, Use:
list(my_set)
to convert it to a list. You can use the newly built list like any normal list in python now.
Simply type:
list(my_set)
This will turn a set in the form {‘1′,’2’} into a list in the form [‘1′,’2’].
I am trying to convert a set to a list in Python 2.6. I’m using this syntax:
first_list = [1,2,3,4]
my_set=set(first_list)
my_list = list(my_set)
However, I get the following stack trace:
Traceback (most recent call last):
File "<console>", line 1, in <module>
TypeError: 'set' object is not callable
How can I fix this?
It is already a list:
>>> type(my_set)
<class 'list'>
Do you want something like:
>>> my_set = set([1, 2, 3, 4])
>>> my_list = list(my_set)
>>> print(my_list)
[1, 2, 3, 4]
EDIT:
Output of your last comment:
>>> my_list = [1,2,3,4]
>>> my_set = set(my_list)
>>> my_new_list = list(my_set)
>>> print(my_new_list)
[1, 2, 3, 4]
I’m wondering if you did something like this:
>>> set = set()
>>> set([1, 2])
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: 'set' object is not callable
I’m not sure that you’re creating a set with this ([1, 2]) syntax, rather a list. To create a set, you should use set([1, 2]).
These brackets are just envelopping your expression, as if you would have written:
if (condition1
and condition2 == 3):
print something
There’re not really ignored, but do nothing to your expression.
Note: (something, something_else) will create a tuple (but still no list).
Review your first line. Your stack trace is clearly not from the code you’ve pasted here, so I don’t know precisely what you’ve done.
>>> my_set=([1,2,3,4])
>>> my_set
[1, 2, 3, 4]
>>> type(my_set)
<type 'list'>
>>> list(my_set)
[1, 2, 3, 4]
>>> type(_)
<type 'list'>
What you wanted was set([1, 2, 3, 4]).
>>> my_set = set([1, 2, 3, 4])
>>> my_set
set([1, 2, 3, 4])
>>> type(my_set)
<type 'set'>
>>> list(my_set)
[1, 2, 3, 4]
>>> type(_)
<type 'list'>
The “not callable” exception means you were doing something like set()() – attempting to call a set instance.
[EDITED]
It’s seems you earlier have redefined “list”, using it as a variable name, like this:
list = set([1,2,3,4]) # oops
#...
first_list = [1,2,3,4]
my_set=set(first_list)
my_list = list(my_set)
And you’l get
Traceback (most recent call last):
File "<console>", line 1, in <module>
TypeError: 'set' object is not callable
Python is a dynamically typed language, which means that you cannot define the type of the variable as you do in C or C++:
type variable = value
or
type variable(value)
In Python, you use coercing if you change types, or the init functions (constructors) of the types to declare a variable of a type:
my_set = set([1,2,3])
type my_set
will give you <type 'set'> for an answer.
If you have a list, do this:
my_list = [1,2,3]
my_set = set(my_list)
Hmmm I bet that in some previous lines you have something like:
list = set(something)
Am I wrong ?
Instead of:
first_list = [1,2,3,4]
my_set=set(first_list)
my_list = list(my_set)
Why not shortcut the process:
my_list = list(set([1,2,3,4])
This will remove the dupes from you list and return a list back to you.
Whenever you are stuck in such type of problems, try to find the datatype of the element you want to convert first by using :
type(my_set)
Then, Use:
list(my_set)
to convert it to a list. You can use the newly built list like any normal list in python now.
Simply type:
list(my_set)
This will turn a set in the form {‘1′,’2’} into a list in the form [‘1′,’2’].