Problem Formulation: Given a string of letters and numbers. How to split the string into substrings of either letters or numbers by using the boundary between a letter and a number and vice versa.
Examples: Have a look at the following examples of what you want to accomplish.
'111A222B333C' ---> ['111', 'A', '222', 'B', '333', 'C']
'Finxter42' ---> ['Finxter', '42']
'Hello world' ---> ['Hello', ' world']
Method 1: re.split()
The re.split(pattern, string)
method matches all occurrences of the pattern
in the string
and divides the string along the matches resulting in a list of strings between the matches. For example, re.split('a', 'bbabbbab')
results in the list of strings ['bb', 'bbb', 'b']
.
# Method 1: re.split() import re s = '111A222B333C' res = re.split('(\d+)', s) print(res) # ['', '111', 'A', '222', 'B', '333', ' C']
The \d
special character matches any digit between 0 and 9. By using the maximal number of digits as a delimiter, you split along the digit-word boundary. Note that you don’t consume the split character by wrapping it into a matching group using the parentheses (...)
. If you leave out the parentheses, it’ll consume the numbers and the result wouldn’t contain any consecutive numbers.
Method 2: re.findall()
The re.findall(pattern, string)
method scans string
from left to right, searching for all non-overlapping matches of the pattern
. It returns a list of strings in the matching order when scanning the string from left to right.
# Method 2: re.findall() import re s = '111A222B333C' res = re.findall('(\d+|[A-Za-z]+)', s) print(res) # ['111', 'A', '222', 'B', '333', 'C']
Method 3: itertools.groupby()
# Method 3: itertools.groupby() from itertools import groupby s = '111A222B333C' res = [''.join(g) for _, g in groupby(s, str.isalpha)] print(res) # ['111', 'A', '222', 'B', '333', 'C']
- The
itertools.groupby(iterable, key=None)
function creates an iterator that returns tuples(key, group-iterator)
grouped by each value ofkey
. We use thestr.isalpha()
function as key function. - The
str.isalpha()
function returnsTrue
if the string consists only of alphabetic characters.
Related Video re.split()
Programmer Humor
There are only 10 kinds of people in this world: those who know binary and those who don’t.
👩🧔♂️
~~~
There are 10 types of people in the world. Those who understand trinary, those who don’t, and those who mistake it for binary.
👩🧔♂️👱♀️
Where to Go From Here?
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