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Hello guys.

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So we are going to continue the discussion with respect to Python.

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And in this video we are going to discuss about filter function.

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Now what exactly is filter function.

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So filter function constructs an iterator from elements of an iterable for which a function returns

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true.

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It is used to filter out items from a list based on a condition.

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So finally, just to understand what this filter function do, it is used to filter out items from a

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list or any iterable based on a condition.

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Okay, so in order to make you understand, let me just go ahead and quickly, uh, write a code for

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you.

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So here I'm going to create a definition.

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Let's say this is my function which will tell whether a number is, uh, even or odd.

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Right.

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Or let's say this particular number is just, uh, this function is just going to check whether the

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number is even and it is just going to return true or false.

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So here if I'm giving num okay.

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And let's say that I'm going to write my condition.

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If num percentile two is double equal to zero, then what we are going to do we are just going to return

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true.

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Right?

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So perfect.

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This works absolutely fine.

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We have seen this kind of function a lot.

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So now if I just go ahead and give my 24.

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So it is just going to give me true because this is obviously a true number.

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But let's say that now I have a list of elements.

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And here I have like one, two, three, four, five, six, seven, eight, nine, ten, something

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like this.

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1112 okay.

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Now I want to apply the same operation on top of this particular element.

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And I want to just filter out which satisfies only this specific condition.

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Right.

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So now focus on the last statement.

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It is used to filter out items from a list based on a condition.

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Right.

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So this is my condition and I want to filter out from this specific list, right?

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So how do I do it?

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Yes, I can actually do it.

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I can just iterate through all this particular elements inside this even function.

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And then I should be able to do it right.

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I should be able to get true, you know, probably append it in another list and get the values.

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But let's do this with the help of filter.

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Okay.

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Now in filter if if you know about filter right filter usually takes first parameter as again function.

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So in this case even is my function.

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And the second parameter will be my list okay.

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Now what this filter does is that whatever condition I have written inside this particular function

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only that will get applied into this and the elements will be taken from the list only, which satisfies

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this condition.

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Right?

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Which is returning true only that elements will be taken out.

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Okay, so here when I say filter even of list.

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And let me just go ahead and probably convert this into a list, you will be able to see that I will

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be getting all the elements that are only even.

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Right.

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So this is a basic example to understand about filter function, right?

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So it applies a kind of filter on the list that we specifically have.

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Okay A very easy, uh, with respect to this.

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Now let's go ahead and see more examples.

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And this time I'm going to take filter with a lambda function.

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Okay.

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So lambda function and I will try to use the same thing.

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Or let me just use some other things like let's say this is my number variable.

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I have like 123456789 okay.

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And then I will say hey do a filter and try to just take out greater than five.

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Okay.

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Greater than five okay.

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Try to create a filter, something like that.

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From this particular list I should only get numbers that are greater than five.

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So now I will just go ahead and write list.

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I will go ahead and use filter function.

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Now let me just go ahead and define my lambda function.

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Write Lambda function will be very simple.

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If I go ahead and write just lambda expression this will this will be my argument.

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Oh, Uh, sorry.

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Uh, yes.

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Argument.

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And I'll be writing my expression.

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That is, x is greater than five and on which list I will basically get, uh, apply this entire thing

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in my numbers.

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Right.

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So this entire function is going to get applied on this particular list.

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Now, once I go ahead and print it, you will be able to see that I will only be getting the elements

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greater than five.

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Right.

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So this is one amazing thing with respect to list.

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And uh, here with a simple just logic, how you are able to use filter.

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Even in the previous video we saw about Lambda also.

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Now I will show you filter operation with uh with multiple condition.

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Okay.

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So here I'm going to say filter with a lambda function, lambda function and multiple conditions.

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So just to make you understand what all things are possible okay.

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So multiple conditions now as usual I'll take this numbers okay.

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Right.

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And let's say I will write a variable even.

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And it should be even I'm writing two check okay.

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Even and greater than five okay.

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So this is my variable that I'm actually going to create two things I'm actually doing.

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Okay.

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First of all I will check whether the number is even or not, will filter out based on the number is

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even or not, and it should be greater than five.

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So in this I will again use list.

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I will again use filter.

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Okay.

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And along with that I will use my lambda x x colon greater than five okay.

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So this is my one condition.

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And I will go ahead and use one logical.

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And so and operation over here I will use and this will be x percentile two or modulus two is double

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equal to zero.

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So these are my two conditions.

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If it is getting satisfied.

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And this will get applied to all my numbers list of numbers that is available over here.

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So inside this lambda function what we are doing we are applying two expression.

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One is x is greater than five and the other one is x modulus two uh is double equal to zero.

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Right now if I go ahead and print.

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So what it is going to do.

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First of all it is going to check whether it is even or not and then whether it is greater than five.

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So out of this elements, you will be able to see that I am able to get only six and eight remaining.

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All elements are odd or less than five.

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Perfect.

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Uh, let's go ahead and see one more way of doing this.

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Okay, now let's say that I want to apply a filter operation not only on list, let's say on dictionaries

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okay.

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So here I will just go ahead and do this okay.

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I will say hey apply filter to check if the age is greater than 25 in dictionary.

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Okay, so here you can basically see I will just create some data.

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And again I have already created this kind of data.

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So let me see from my which functions map function I think I have I've actually used this kind of data.

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Uh, yeah.

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So this is my people data.

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Okay.

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So here I have specifically people data.

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I will use this same thing okay.

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Just trying to save time.

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Okay.

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Now from this I will create a function where I'll say age greater than 25.

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Okay.

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And uh, let's say I'll just make some more data over here, I will cope.

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I'll put over here.

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I'll say Jack.

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Then along with this, I'll say, John, age will be 25.

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Okay.

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And then what we are going to basically do, we are going to create a function here.

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We are going to give the person information, one item person information.

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And then we are just going to return the person of age, right?

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And this age should be greater than 25.

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And based on this, either it will return true or false.

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Right now we are just going to apply this with the help of filter.

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And we will use this particular function.

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So I'll say filter.

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And this will be my age greater than 25 along with my people because I need to apply this on my entire.

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Um, uh, what to say collection that is iterable.

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And then I'll try to convert this into a list.

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So if I go ahead and print it.

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So here you'll be able to see name age age 32 and 33, because this particular condition checks only

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and returns only the age based on the age condition greater than 25, it will return those specific

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records.

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And yes, from this particular filter operation, you'll be able to see that I'm able to do this.

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right.

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So these are some of the amazing operations that you can do with filter.

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So I would definitely like to put some kind of conclusions.

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And I'm doing that particular thing with respect to every video that I, uh, record in this.

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So here these are some of the conclusions.

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So here you can see the filter function is a powerful tool for creating iterators that filter items

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out of an iterable based on a function.

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It is commonly used for data cleaning filter objects and removing unwanted elements.

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By mastering filter, you can write more concise and efficient code for processing and manipulating

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collections in Python.

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So yes, this was about filter.

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Now as we go ahead, we will be discussing about and again we will be reusing all these things.

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But I think you got a clear idea about functions different types of functions.

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Anonymous function Lambda function.

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Map function.

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Filter function.

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Uh so yes, this was it for my side.

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I will see you all in the next video.

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Thank you.

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Take care.