8.9: Lists and Strings
- Page ID
- 3140
A string is a sequence of characters and a list is a sequence of values, but a list of characters is not the same as a string. To convert from a string to a list of characters, you can use list
:
>>> s = 'spam'
>>> t = list(s)
>>> print(t)
['s', 'p', 'a', 'm']
Because list
is the name of a built-in function, you should avoid using it as a variable name. I also avoid the letter l
because it looks too much like the number 1
. So that's why I use t
.
The list
function breaks a string into individual letters. If you want to break a string into words, you can use the split
method:
>>> s = 'pining for the fjords'
>>> t = s.split()
>>> print(t)
['pining', 'for', 'the', 'fjords']
>>> print(t[2])
the
Once you have used split
to break the string into a list of words, you can use the index operator (square bracket) to look at a particular word in the list.
You can call split
with an optional argument called a delimiter that specifies which characters to use as word boundaries. The following example uses a hyphen as a delimiter:
>>> s = 'spam-spam-spam'
>>> delimiter = '-'
>>> s.split(delimiter)
['spam', 'spam', 'spam']
join
is the inverse of split
. It takes a list of strings and concatenates the elements. join
is a string method, so you have to invoke it on the delimiter and pass the list as a parameter:
>>> t = ['pining', 'for', 'the', 'fjords']
>>> delimiter = ' '
>>> delimiter.join(t)
'pining for the fjords'
In this case the delimiter is a space character, so join
puts a space between words. To concatenate strings without spaces, you can use the empty string, "", as a delimiter.