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[no audio]

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Friends here our concept is

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'compile' operation or method of 're' module

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See we know that we have different types of operations in

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your 're' module.

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Let me go with some of them so that I can explain the usage

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of 'compile' operation. Suppose

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I have some string here, now

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I need to write a pattern such that I want to find 'python'

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is there a given string or not.

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Then just let me write a pattern.

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Suppose first I will go and work with 'findall' operation.

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How many 'python' are there in a given string?

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So for that I'm writing simply a pattern. See that, first

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I'm writing simply 'python'. But I want to look for a word,

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then you have to write with '\b' starting and ending, then

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exactly word matching. Now, first

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let me simply 'print(re.findall)', from your pattern

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in a given string how many matchings are there.

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See the result. You're getting only one 'python', but we have

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here 'python', and here also 'python'.

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Anyway, these are 'python2' and 'python3'. No problem.

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So here capital 'P', and here small 'p'.

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Then you can write in two ways to identify this small 'p' 'python',

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capital 'P' 'Python', that is

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if you write in square brackets, very first character

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it maybe small 'p', or capital 'P', [pP]. Now see the result.

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[no audio]

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Or instead of that, instead of that suppose

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if you don't want to consider about case sensitivity simply

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you can write a flag here. If you remember there is an option called

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'flags'. Simply write 're.I'.

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Now see the result. You're going to get. 'python', small and

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capital. Now, along with that

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I need to identify 'python2' or 'python3' also. Then at the

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end 2 or 3 is optional, right. Then there is a '?'.

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So the '?' meaning is either 2 or 3,

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maybe once or none,

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that is the meaning of your '?'. See we already

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discussed about the rules to create your patterns in our

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previous videos, right?

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So based on that I am creating this pattern. That's fine.

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Now, let me run this and see the result. Now you're going

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to get 'python', capital P 'Python', 'python2', and 'python3'.

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So that is the usage of patterns actually,

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I mean 'regex', Regular Expressions.

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That's fine. Now,

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suppose I am using different operations on my same pattern,

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suppose I am using 're.search',

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[no audio]

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your pattern, then in a given string. So what is your given

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string, this one. Now see the result.

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You're getting some object.

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Yes, there is a match.

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So if there is a match, then you can look for your required,

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I mean, what is the match and where is the matching position

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occurred in a given string, you can go with that like, 'start',

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'end', 'group', right,

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we have those operations. That's fine.

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Now, let me do one more operation.

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So I want to print, I want to split my given string based

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on my pattern.

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So what is my pattern? So normally on your strings you have

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a split operation, if you go with that you can able to split your given

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string based on one single string, but here I am going to

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divide my given string based on either 'python' or capital 'P'

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'python' or 'python2' or 'python3', simply wherever these four

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words are there in a given string there split will happen.

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So that is the usage of 'split' from your Regular Expression.

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Now, let me write your string and see the result.

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Yes. So likewise, you can use your different operations.

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Right. But here, suppose sometimes you are going to use same

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pattern multiple times in your given code,

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I mean, whatever the code you're writing, in your code

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you are going to use your pattern,

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whatever the pattern you have that pattern you are going to

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use multiple times.

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So whenever if you are using multiple times,

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instead of using in this way

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we are going with 'compile' operation. First see the code so

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that you can understand then I will explain you once again.

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Now, I am creating pattern object, pattern object.

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Nothing is there. Simply 're.compile',

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whatever the pattern you have. That's it.

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Now if you print your pattern object.

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[no audio]

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First see the result.

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What happened?

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[no audio]

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Sorry, spelling mistake.

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Yeah, see that. You are getting a pattern but in terms of object.

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Now, this is a object not like simply your 'python', something like

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that. Your 'Python' is converting now your pattern into an

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object. Now on this object instead of performing your operations

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in this way 're.search', 're.findall', 're.split',

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or whatever the operation you have, instead of that directly

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you can perform your operation on this object.

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[no audio]

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See that. Sorry, 'pat_obj', 'print', suppose

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'pat_obj.', your operation,

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then only string because already pattern is there in this

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object, only string, your string.

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[no audio]

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Now see the result. Whatever the output previously you got

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same output you're getting here.

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Let me enable

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your previous output, without 'compile' operation whatever

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the way we are using to use 'search',

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[no audio]

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is there any difference between these two, first output and

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last output? There is no difference.

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But while comparing first procedure, I mean sixth line syntax,

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your 13th line is having more efficiency.

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So speed of operation is very high if we use simply pattern objects.

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[no audio]

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Not only for that, you can use all operations. Now,

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let me disable your normal direct operations.

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Now I am using, you can use, for each and every operation you

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can use this pattern object.

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'pat_obj.findall', then simply your string.

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What is the String? Only pattern is there in this object guys.

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So now this pattern object is supporting to perform your

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all Regular Expressions without any 're' module.

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See that. Previously to perform your operations you're using

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're.', but now we are using 'pat_ob.'. So already

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inside of this 'pat_ob', your 're' is there and

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your 'compile' pattern is also there. Now directly we are doing

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our operation on that. See the result.

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'pat_ob.findall("python"). What happened?

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Where is it? Yeah.

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See that. Previously

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we used ignore case sensitivity, now in 'compile' operation

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you can also use flags then only you can get your remaining

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pythons, because we are looking for capital 'P', right. Now see

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that 'flags=re.I'. So 'compile' operation or method

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is also supporting 'flags' operations. Now see the result.

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[no audio]

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That's it. So guys, nothing is there. Let me write one simple, suppose

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if you are using 're.findall', your pattern, then your

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string, this we are doing in this way.

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[no audio]

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're.compile()', your pattern, '.findall'. This is exactly equal to this thing.

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I mean any operation you can compare in this way.

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So 're.findall', now

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we are doing 're.compile'. First

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we are creating an object using your patterns, on that object

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we are performing our operation.

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You can also store this output into some variable.

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That's what I did.

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[no audio]

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Right. Nothing is there. See most of the people will get confusion

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why we need to use 'compile' operation? Simple, whenever if

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you are using same pattern in different places in your code,

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then instead of in that way just try to compile your object,

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try to create 'compile' object first. On that object

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you just try to perform your required operation in

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this way, so that your code is efficient, speed of operation is high.

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Other than that nothing is there.

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Okay. Okay guys,

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thank you for watching this video.

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[no audio]