Create multidimensional numpy array from lists

Question

I have three lists,

list1=['10','20','30']

list2=['40','50','60']

list3=['70','80','90']

I want to create a numpy array from these lists. I am using the foloowing code:

import numpy as np
list1=['10','20','30']
list2=['40','50','60']
list3=['70','80','90']

data = np.array([[list1],[list2],[list3]])
print data

I am getting output as:

 [[['10' '20' '30']]
  [['40' '50' '60']]
  [['70' '80' '90']]]

But I am expecting output as:

[[10 20 30]
 [40 50 50]
 [70 80 90]]

Can anybody plz help me on this?

Community · Accepted Answer · 2020-06-20 09:12:55Z

2

Specify dtype:

>>> import numpy as np
>>> list1=['10','20','30']
>>> list2=['40','50','60']
>>> list3=['70','80','90']
>>> np.array([list1, list2, list3], dtype=int)
array([[10, 20, 30],
       [40, 50, 60],
       [70, 80, 90]])

According to numpy.array documentation:

dtype : data-type, optional

The desired data-type for the array. If not given, then the type will be determined as the minimum type required to hold the objects in the sequence. ...

edited Jun 20, 2020 at 9:12

CommunityBot

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answered Dec 20, 2013 at 9:17

falsetru

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2 Comments

alko Over a year ago

It's probably worthwhile to mention that specifying dtype results in datatype conversion from strings to ints under the hood.

falsetru Over a year ago

@alko, Thank you for comment. I updated the answer with quotation from the documentation.

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