CODEWITHSUNDEEP
python
dorothy
dorothy

Reputation: 1243

Playing with the Python zip function

Say I wanted to find "greater than" in 2 lists.

a = [1,2,3]
b = [0, 0.1, 4]
map( <something>, zip(a,b))

I tried operator module. It has a operator.gt() method. But i couldn't find a way to make use of it with zip. any ideas? Edit: The output is just a True value if any one of the them is True.

thanks

Upvotes: 2

Views: 1678

Answers (4)

Micke
Micke

Reputation: 2309

To just compare the items in lists a with items in b, you don't event have to use zip():

>>> a = [1, 2, 3] 
>>> b = [0, 0.1, 4]
>>> map(operator.gt, a, b)
[True, True, False]
>>>

But on the other hand you've not specified what kind of output you're expecting.

EDIT:

To effectively OR the result, wrap it with any(). Like so:

>>> any(map(operator.gt, a,b))
True

Upvotes: 8

unutbu
unutbu

Reputation: 879461

In [6]: a = [1,2,3]

In [7]: b = [0, 0.1, 4]

In [8]: [max(a_,b_) for a_,b_ in zip(a,b)]
Out[8]: [1, 2, 4]

or, pithier,

In [9]: map(max, zip(a,b))
Out[9]: [1, 2, 4]

If you want of list of True/False values (True where the item in a is greater than the item in b, and False otherwise), you could use itertools.starmap with operator.gt:

In [15]: import itertools as IT

In [17]: list(IT.starmap(operator.gt, zip(a,b)))
Out[17]: [True, True, False]

Upvotes: 2

John Greenall
John Greenall

Reputation: 1690

numpy is ideal for this kind of stuff if you don't mind the additional dependancy.

import numpy as np
a = np.array([1,2,3])
b = np.array([0, 0.1, 4])
c = a > b

Upvotes: 1

Ankur Ankan
Ankur Ankan

Reputation: 3066

a = [1,2,3]
b = [0, 0.1, 4]

map (max, zip(a,b))

Output: [1, 2, 4]

Upvotes: 2

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