#100DaysOfCode in Python Transcripts
Chapter: Days 28-30: Regular Expressions
Lecture: Using re.sub for string replacing
Login or
purchase this course
to watch this video and the rest of the course contents.
0:00
Welcome back to the last section on the regex lesson.
0:03
This video will show you advanced string replacing
0:06
using re.sub.
0:08
For example, we have a string here
0:09
on doing the 100 days of code, 200 days of Django,
0:12
and, of course, 365 days of PyBites.
0:16
So you're doing a simple string replacement.
0:20
It's a bit ugly, right.
0:22
So this will work but.
0:25
When you start to do things multiple times,
0:28
you have to think about a better way to do it.
0:31
So let's use re.sub
0:34
to make a more flexible replacement regex.
0:38
So re.sub...
0:40
raw string
0:42
and I want one or more digits
0:44
and I just want to replace those by 100.
0:48
And I do that on the text
0:50
and this works as well and it's more flexible
0:54
because if there are will be like five or six
0:57
of these hashtags with different integers,
1:00
they all would work.
1:03
Now let's look at a more advanced example
1:07
where we also want to capture the thing we replaced.
1:12
Say, for the same string,
1:14
I want to replace the thing after the days off.
1:17
So all should be Python, but we want to respect the integer
1:21
so I want to have 100 days of Python,
1:23
200 days of Python, and 365 days of Python.
1:26
Doesn't really make sense in a sentence
1:28
but it does for our exercise.
1:30
And the way to do that is to write a re.sub...
1:35
raw string.
1:37
And let's define the regular expression as a literal hash.
1:45
One or more digits.
1:47
Hard-code days of
1:51
one or more alphanumeric characters.
1:55
Here, you see these capturing parenthesis again.
2:00
I'm going to use that in a replacement part
2:02
which is the second argument
2:04
and I can reference that with backslash one.
2:08
So what this does is it takes the...
2:12
match of hashtag...
2:15
digits days off
2:17
and I'm going to put that in the replacement string.
2:21
And then I want to hard-code Python
2:25
and I want to do this on text.
2:28
And there you go.
2:29
Awesome, I'm doing 100 days of Python, 200 days of Python,
2:33
and, of course, 365 days of Python.
2:35
That's a wrap.
2:37
I hope you enjoyed this and got a better feeling
2:40
of how to write your regexes in Python.
2:44
Of course it's not a complete list of all the features
2:47
and that's why in day two I will provide you
2:50
some more resources and things you can check out.
