Pandas: create new column in df with random integers from range

Issue

I have a pandas data frame with 50k rows. I’m trying to add a new column that is a randomly generated integer from 1 to 5.

If I want 50k random numbers I’d use:

df1['randNumCol'] = random.sample(xrange(50000), len(df1))

but for this I’m not sure how to do it.

Side note in R, I’d do:

sample(1:5, 50000, replace = TRUE)

Any suggestions?

Solution

One solution is to use numpy.random.randint:

import numpy as np
df1['randNumCol'] = np.random.randint(1, 6, df1.shape[0])

Or if the numbers are non-consecutive (albeit slower), you can use this:

df1['randNumCol'] = np.random.choice([1, 9, 20], df1.shape[0])

In order to make the results reproducible you can set the seed with numpy.random.seed (e.g. np.random.seed(42))

Answered By – Matt

Answer Checked By – Robin (AngularFixing Admin)

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