How to substitute numbers of a numpy array with strings of a list in python

Question

I have a numpy array and want to replace its values with some strings. I checked this solution but could not solve my issue. My strings are in a list:

names=['base', 'middle', 'top']

my list has three strings and it means I have also three numbers in my array:

import numpy as np
numbers=np.array([[3., 1., 2., 2.], [1., 2., 3., 1.]])

To map names with numbers I have this logic: from the first name until the last, numbers decrease. I mean first name matches the highest number ('base' : 3.), next name the second highest ('middle' : 2.) and last name equals the lowest ('top' : 1.). Finally I want to have my array as:

subs_arr= np.array([['base', 'top', 'middle', 'middle'], ['top', 'middle', 'base', 'top']])

Is ther any way to do it automatically (without the need for mapping names with numbers) in python? I do appreciate any help in advance.

subs_arr = np.array(names)[(numbers-1).astype(np.int)] where numbers should start with 0 since a python index start with 0. However this solution is the same as the one suggested in your link, so I'm voting to close this question. — obchardon
– obchardon, Commented Jun 2, 2021 at 8:22
Does this answer your question? Replace values of a numpy array by values from another numpy array — obchardon
– obchardon, Commented Jun 2, 2021 at 8:25
Dear @obchardon, thanks for your help. Honestly, after reading that solution I still could not figure out my problem. — Link_tester
– Link_tester, Commented Jun 2, 2021 at 8:29

yann ziselman · Accepted Answer · 2021-06-02 08:25:19Z

2

How about smth like this:

import numpy as np
numbers = np.array([[3., 1., 2., 2.], [1., 2., 3., 1.]]).astype(int)-1
names = np.array(['top', 'middle', 'base'])

subs_arr = names[numbers]

output:

subs_arr = 
[['base' 'top' 'middle' 'middle']
 ['top' 'middle' 'base' 'top']]

answered Jun 2, 2021 at 8:25

yann ziselman

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2 Comments

Link_tester Over a year ago

Dear @yan ziselman, maybe replacing 1 with np.min(numbers) works better, isnt it?

yann ziselman Over a year ago

that would depend on the use case and how you form the array 'numbers'

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