CODEWITHSUNDEEP
pythonfloating-pointintegerpython-3.6negative-number
Engine
Engine

Reputation: 141

How can I check if an integer or float number in a list is positive or negative in sign?

I'm using Python 3.6. What would be an efficient way to check if a float or integer number within a list is negative or positive?

I want to iterate through a list, retrieving only the indexes of numbers of a particular sign.

For example:

x = [1,-7, 9, 3, 6, -3 ]

y = [ i for i in x if i    **____**   ]

I feel like its right under my nose, but its just not coming to me.

Upvotes: 1

Views: 4767

Answers (1)

martineau
martineau

Reputation: 123463

Is this what you mean?

x = [1,-7, 9, 3, 6, -3 ]

y = [elem for elem in x if elem < 0]

z = [elem for elem in x if elem > 0]

print(y)  # -> [-7, -3]
print(z)  # -> [1, 9, 3, 6]

In this somewhat special case, you could use a slightly different approach and create both lists simultaneously:

x = [1,-7, 9, 3, 6, -3 ]

yz = y, z = [], []
for elem in x:
    yz[elem > 0].append(elem) if elem else None

print(y)  # -> [-7, -3]
print(z)  # -> [1, 9, 3, 6]

Upvotes: 5

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