CODEWITHSUNDEEP
pythonnumpy
helloPeople
helloPeople

Reputation: 47

How to Return True/False For Items in One List Found in Another List

I am trying to work on a function that will take two lists, and create a new list as long as the first, and return True or False if each item in the list is found in the second list. I am also incorporating the use of numpy in the event I want to use a large list.

I tried the below but I was unable to produce the result that I wanted. Any assistance is appreciated.

import numpy as np

def a_is_in(a, b):
    list1 = np.array(a)
    list2 = np.array(b)
    if list1 in list2:
        return False
    else:
        return True
    return

a = [3, 4, 8, 10, 11, 13]
b = [3, 6, 7, 13]
_is_in = a_is_in(a, b)
print(_is_in)

import numpy as np

def a_is_in(a, b):
    list1 = np.array(a)
    list2 = np.array(b)
    result = lambda list1, list2: any(i in list2 for i in list1)
    return result

a = [3, 4, 8, 10, 11, 13]
b = [3, 6, 7, 10, 13]
_is_in = a_is_in(a, b)
print(_is_in)

The returned result I am looking for is a list that looks like this: [True, False, False, True, False, True]

Thank you for your time.

Upvotes: 0

Views: 3229

Answers (3)

Farhood ET
Farhood ET

Reputation: 1551

If you are using numpy you can use np.isin function.

# arr1 and arr2 are your numpy arrays.
result = np.isin(arr1, arr2)

Upvotes: 2

Sami B. Torres
Sami B. Torres

Reputation: 23

I have tried to do this using a simple syntax (as a beginner I prefer not to go too far). But I think using a for loop for this can be a bit too heavy and there might be other simpler options.

def a_is_in(a, b):
    result =[]
    for i in range(0,len(a)):
        if a[i] in b:
            result.append(True)
        else:
            result.append(False)
    return(result)

Upvotes: 1

Sheldore
Sheldore

Reputation: 39072

You can use simple list comprehension and use i in b as the condition which will return either True or False

First example

a = [3, 4, 8, 10, 11, 13]
b = [3, 6, 7, 13]
_is_in = [i in b for i in a]
print(_is_in)
# [True, False, False, False, False, True]

Second example

a = [3, 4, 8, 10, 11, 13]
b = [3, 6, 7, 10, 13]
_is_in = [i in b for i in a]
print(_is_in)
# [True, False, False, True, False, True]

Upvotes: 2

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