How to replace a value in array in numpy python

Question

I have a very basic question in numpy arrays:

My array looks something like this:

Array = [["id1", "1.0"],["id2", "0.0"]]

I want to read the second element of the array and replace with an another character. Its like

for i in range(0,len(array)):
    if array[i] == "0.0":
        array[i] = "ClassA"
    else
        array[i] = "ClassB"

How to achieve this. I am not able to read "0.0" or "1.0" correctly. Please help.

@hiroprotagonist - I am sorry if that is the case, the element type is numpy.ndarray. Is this and the numpy arrays are different? And checked for the dtype of the element - it is "str18912". — Doubt Dhanabalu
– Doubt Dhanabalu, Commented Aug 16, 2017 at 9:28
@PrakashPalnati - Thank you for pointing me out the mistake. I have updated the question. — Doubt Dhanabalu
– Doubt Dhanabalu, Commented Aug 16, 2017 at 10:01

M3RS · Accepted Answer · 2017-08-16 13:21:40Z

2

You have two arrays inside an array. The below code should work:

array = [["id1", "1.0"],["id2", "0.0"]]

for item in array:
    if item[1] == "0.0":
        item[1] = "ClassA"
    else:
        item[1] = "ClassB"

edited Aug 16, 2017 at 13:21

answered Aug 16, 2017 at 9:30

M3RS

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Comments

hiro protagonist · Accepted Answer · 2017-08-16 09:32:54Z

you are missing ,s in the definition of your array. your array is the same as this: [["id11.0"], ["id20.0"]] (strings just get concatenated). if your arrays are numpy arrays then this is the way they are represented (printed). but that does not work as input...

starting from your code you could to this:

array = [["id1", "1.0"], ["id2", "0.0"]]

for i, (id_, number) in enumerate(array):
    if number == "0.0":
        array[i] = [id_, "ClassA"]
    else:
        array[i] = [id_, "ClassB"]

or, more elegant, use a list-comprehension:

array = [[id_, "ClassA"] if number == "0.0" else [id_, "ClassB"]  
         for id_, number in array ]

Protagnoistn - Thank you very much for the response. This also has worked for me.

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