CODEWITHSUNDEEP
pythonlist
machinery
machinery

Reputation: 6290

Getting elements in certain range of list

I have a Python list, for example list = [1,2,3,4,5,6,7,8,9]. In addition, I have another list list2 = ['a','b','c','d','e','f','g','h','j']. Now I would like to do the following:

idx = (list > 3) & (list < 7)
list2 = list2[idx]

This should yield ['d','e','f']. Of course, this is not possible with lists. How can this be done with lists?

Upvotes: 3

Views: 75

Answers (3)

iGian
iGian

Reputation: 11183

Option with list comprehension accessing elements by index:

res = [ list2[idx] for idx, e in enumerate(list1) if 7 > e > 3 ]
print(res) #=> ['d', 'e', 'f']

To get the elements from both the lists:

[ [list2[idx], e] for idx, e in enumerate(list1) if 7 > e > 3 ]
#=> [['d', 4], ['e', 5], ['f', 6]]

Then transpose:

res1, res2 = [ list(i) for i in zip(*[ [list2[idx], e] for idx, e in enumerate(list1) if 7 > e > 3 ]) ]
print (res1, res2 ) #=> ['d', 'e', 'f'] [4, 5, 6]

Upvotes: 0

Ajax1234
Ajax1234

Reputation: 71451

You can use zip:

l1 = [1,2,3,4,5,6,7,8,9]
l2 = ['a','b','c','d','e','f','g','h','j']
result = [a for a, b in zip(l2, l1) if 3 < b < 7]

Output:

['d', 'e', 'f']

To get the reduced list as well:

result, reduced = map(list, zip(*[[a, b] for a, b in zip(l2, l1) if 3 < b < 7]))

Output:

['d', 'e', 'f'] #result
[4, 5, 6] #reduced

Upvotes: 6

Dadu Khan
Dadu Khan

Reputation: 379

Try this:

#Make sure all lists are numpy arrays.
import numpy as np
idx = np.where((list > 3) & (list < 7))
list2 = list2[idx]

Upvotes: 1

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