How do I split a string into a list of characters?

Question

How do I split a string into a list of characters? str.split does not work.

"foobar"    →    ['f', 'o', 'o', 'b', 'a', 'r']

Answer 1

Use the list constructor:

>>> list("foobar")
['f', 'o', 'o', 'b', 'a', 'r']

list builds a new list using items obtained by iterating over the input iterable. A string is an iterable -- iterating over it yields a single character at each iteration step.

Answer 2

You take the string and pass it to list()

s = "mystring"
l = list(s)
print l

Answer 3

You can also do it in this very simple way without list():

>>> [c for c in "foobar"]
['f', 'o', 'o', 'b', 'a', 'r']

Answer 4

If you want to process your String one character at a time. you have various options.

uhello = u'Hello\u0020World'

Using List comprehension:

print([x for x in uhello])

Output:

['H', 'e', 'l', 'l', 'o', ' ', 'W', 'o', 'r', 'l', 'd']

Using map:

print(list(map(lambda c2: c2, uhello)))

Output:

['H', 'e', 'l', 'l', 'o', ' ', 'W', 'o', 'r', 'l', 'd']

Calling Built in list function:

print(list(uhello))

Output:

['H', 'e', 'l', 'l', 'o', ' ', 'W', 'o', 'r', 'l', 'd']

Using for loop:

for c in uhello:
    print(c)

Output:

H
e
l
l
o

W
o
r
l
d

Answer 5

If you just need an array of chars:

arr = list(str)

If you want to split the str by a particular delimiter:

# str = "temp//temps" will will be ['temp', 'temps']
arr = str.split("//")

Answer 6

I explored another two ways to accomplish this task. It may be helpful for someone.

The first one is easy:

In [25]: a = []
In [26]: s = 'foobar'
In [27]: a += s
In [28]: a
Out[28]: ['f', 'o', 'o', 'b', 'a', 'r']

And the second one use map and lambda function. It may be appropriate for more complex tasks:

In [36]: s = 'foobar12'
In [37]: a = map(lambda c: c, s)
In [38]: a
Out[38]: ['f', 'o', 'o', 'b', 'a', 'r', '1', '2']

For example

# isdigit, isspace or another facilities such as regexp may be used
In [40]: a = map(lambda c: c if c.isalpha() else '', s)
In [41]: a
Out[41]: ['f', 'o', 'o', 'b', 'a', 'r', '', '']

See python docs for more methods

Answer 7

The task boils down to iterating over characters of the string and collecting them into a list. The most naïve solution would look like

result = []
for character in string:
    result.append(character)

Of course, it can be shortened to just

result = [character for character in string]

but there still are shorter solutions that do the same thing.

list constructor can be used to convert any iterable (iterators, lists, tuples, string etc.) to list.

>>> list('abc')
['a', 'b', 'c']

The big plus is that it works the same in both Python 2 and Python 3.

Also, starting from Python 3.5 (thanks to the awesome PEP 448) it's now possible to build a list from any iterable by unpacking it to an empty list literal:

>>> [*'abc']
['a', 'b', 'c']

This is neater, and in some cases more efficient than calling list constructor directly.

I'd advise against using map-based approaches, because map does not return a list in Python 3. See How to use filter, map, and reduce in Python 3.

Answer 8

split() inbuilt function will only separate the value on the basis of certain condition but in the single word, it cannot fulfill the condition. So, it can be solved with the help of list(). It internally calls the Array and it will store the value on the basis of an array.

Suppose,

a = "bottle"
a.split() // will only return the word but not split the every single char.

a = "bottle"
list(a) // will separate ['b','o','t','t','l','e']

Answer 9

Unpack them:

word = "Paralelepipedo"
print([*word])

Answer 10

To split a string s, the easiest way is to pass it to list(). So,

s = 'abc'
s_l = list(s) #  s_l is now ['a', 'b', 'c']

You can also use a list comprehension, which works but is not as concise as the above:

s_l = [c for c in s]

There are other ways, as well, but these should suffice. Later, if you want to recombine them, a simple call to "".join(s_l) will return your list to all its former glory as a string...

Answer 11

You can use extend method in list operations as well.

>>> list1 = []
>>> list1.extend('somestring')
>>> list1
['s', 'o', 'm', 'e', 's', 't', 'r', 'i', 'n', 'g']

Answer 12

If you wish to read only access to the string you can use array notation directly.

Python 2.7.6 (default, Mar 22 2014, 22:59:38) 
[GCC 4.8.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> t = 'my string'
>>> t[1]
'y'

Could be useful for testing without using regexp. Does the string contain an ending newline?

>>> t[-1] == '\n'
False
>>> t = 'my string\n'
>>> t[-1] == '\n'
True

Answer 13

Well, much as I like the list(s) version, here's another more verbose way I found (but it's cool so I thought I'd add it to the fray):

>>> text = "My hovercraft is full of eels"
>>> [text[i] for i in range(len(text))]
['M', 'y', ' ', 'h', 'o', 'v', 'e', 'r', 'c', 'r', 'a', 'f', 't', ' ', 'i', 's', ' ', 'f', 'u', 'l', 'l', ' ', 'o', 'f', ' ', 'e', 'e', 'l', 's']

Answer 14

from itertools import chain

string = 'your string'
chain(string)

similar to list(string) but returns a generator that is lazily evaluated at point of use, so memory efficient.

Answer 15

Here is a nice script that will help you find which method is most efficient for your case:

import timeit
from itertools import chain

string = "thisisthestringthatwewanttosplitintoalist"

def getCharList(str):
  return list(str)

def getCharListComp(str):
  return [char for char in str]

def getCharListMap(str):
  return list(map(lambda c: c, str))

def getCharListForLoop(str):
  list = []
  for c in str:
    list.append(c)

def getCharListUnpack(str):
  return [*str]

def getCharListExtend(str):
  list = []
  return list.extend(str)

def getCharListChain(str):
  return chain(str)
 
time_list = timeit.timeit(stmt='getCharList(string)', globals=globals(), number=1)
time_listcomp = timeit.timeit(stmt='getCharListComp(string)', globals=globals(), number=1)
time_listmap = timeit.timeit(stmt='getCharListMap(string)', globals=globals(), number=1)
time_listforloop = timeit.timeit(stmt='getCharListForLoop(string)', globals=globals(), number=1)
time_listunpack = timeit.timeit(stmt='getCharListUnpack(string)', globals=globals(), number=1)
time_listextend = timeit.timeit(stmt='getCharListExtend(string)', globals=globals(), number=1)
time_listchain = timeit.timeit(stmt='getCharListChain(string)', globals=globals(), number=1)

print(f"Execution time using list constructor is {time_list} seconds")
print(f"Execution time using list comprehension is {time_listcomp} seconds")
print(f"Execution time using map is {time_listmap} seconds")
print(f"Execution time using for loop is {time_listforloop} seconds")
print(f"Execution time using unpacking is {time_listunpack} seconds")
print(f"Execution time using extend is {time_listextend} seconds")
print(f"Execution time using chain is {time_listchain} seconds")