TypeError: data type not understood while creating a numpy array

Question

Having a list of boolean conditions list I would like to generate a matrix with the lists that have False or True values

For this example values = [[True, False], [False], [True], [True, False]] the result will be

    False  True
0   1       1
1   1       0
2   0       1
3   1       1

I tried to do that as following:

nodes = [True, False]
values = [[True, False], [False], [True], [True, False]]
res = np.array([[int(cond in vals) for vals in values] for cond in nodes],
                dtype=[(node, int) for node in nodes])

But I am getting the error TypeError: data type not understood

what is the dtype suppose to represent? I thought it just needed to be int to specify that each value in the array is an int — Tadhg McDonald-Jensen
– Tadhg McDonald-Jensen, Commented May 10, 2016 at 13:59
let np.array analyse your data : In [348]: array( [[True, False], [False], [True], [True, False]]) -> Out[348]: array([[True, False], [False], [True], [True, False]], dtype=object) — B. M.
– B. M., Commented May 10, 2016 at 14:05
have you tried dtype=int? I think that is all you need for this to work... — Tadhg McDonald-Jensen
– Tadhg McDonald-Jensen, Commented May 10, 2016 at 14:06

SparkAndShine · Accepted Answer · 2016-05-10 14:10:02Z

3

Try dtype=int, and then we have,

import numpy as np 

nodes = [True, False]
values = [[True, False], [False], [True], [True, False]]
res = np.array([[cond in vals for vals in values] for cond in nodes], dtype=int)

print(res)
# Output
[[1 0 1 1]
 [1 1 0 1]]

edited May 10, 2016 at 14:10

answered May 10, 2016 at 14:05

SparkAndShine

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1 Comment

Tadhg McDonald-Jensen Over a year ago

when the dtype is specified you don't even need to explicitly cast to that same type, so int(cond in vals) is a bit redundant, it could just be cond in vals

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