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Convert a list of characters into a string


Question

If I have a list of chars:

a = ['a','b','c','d']

How do I convert it into a single string?

a = 'abcd'
2013/05/02
1
421
5/2/2013 9:44:52 AM

Accepted Answer

Use the join method of the empty string to join all of the strings together with the empty string in between, like so:

>>> a = ['a', 'b', 'c', 'd']
>>> ''.join(a)
'abcd'
2010/12/19
597
12/19/2010 5:20:50 AM

This works in many popular languages like JavaScript and Ruby, why not in Python?

>>> ['a', 'b', 'c'].join('')
Traceback (most recent call last):
   File "<stdin>", line 1, in <module>
AttributeError: 'list' object has no attribute 'join'

Strange enough, in Python the join method is on the str class:

# this is the Python way
"".join(['a','b','c','d'])

Why join is not a method in the list object like in JavaScript or other popular script languages? It is one example of how the Python community thinks. Since join is returning a string, it should be placed in the string class, not on the list class, so the str.join(list) method means: join the list into a new string using str as a separator (in this case str is an empty string).

Somehow I got to love this way of thinking after a while. I can complain about a lot of things in Python design, but not about its coherence.

2019/09/30

If your Python interpreter is old (1.5.2, for example, which is common on some older Linux distributions), you may not have join() available as a method on any old string object, and you will instead need to use the string module. Example:

a = ['a', 'b', 'c', 'd']

try:
    b = ''.join(a)

except AttributeError:
    import string
    b = string.join(a, '')

The string b will be 'abcd'.

2017/01/04

This may be the fastest way:

>> from array import array
>> a = ['a','b','c','d']
>> array('B', map(ord,a)).tostring()
'abcd'
2012/07/10

The reduce function also works

import operator
h=['a','b','c','d']
reduce(operator.add, h)
'abcd'
2013/08/21

If the list contains numbers, you can use map() with join().

Eg:

>>> arr = [3, 30, 34, 5, 9]
>>> ''.join(map(str, arr))
3303459
2020/02/18

Source: https://stackoverflow.com/questions/4481724
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