ValueError: NumPy boolean array indexing assignment cannot assign 0 input values to the N output values where the mask is true

Question

I have a Dicom file and i would like to apply a number of masks with different operations in the voxels. However, I would like to keep the positions in the initial array because I want to reconstruct the image. This is what I have done:

#The dicom data    
a=dicomm_data.pixel_array
#start function
my_modified_array = np.zeros_like(a)
#mask 1
m1=a[(a>limit_1) & (a<limit_2)]
m1=m1*chosen_number1 + chose_number2
my_modified_array [(a>limit_1) & (a<limit_2)] = m1

#mask 2
m2=a[(a>limit_2+1) & (a<limit_3)]
m2=m1*chosen_number3+chosen_number_4
my_modified_array [(a>limit_2+1) & (a<limit_3)] = m2

and I continue with more masks. However, I am receiving the mentioned in the title error. I have read another post which uses the numpy.where function but still cannot fix it.

What is a1? It suddenly appears in an expression without being mentioned before. — Sven Marnach
– Sven Marnach, Commented Nov 3, 2014 at 10:19

Warren Weckesser · Accepted Answer · 2014-11-03 11:05:48Z

1

You'll get the error when m1 is an empty array but a[(a>limit_2+1) & (a<limit_3)] is not empty. I think

m2=m1*chosen_number3+chosen_number_4

should be

m2=m2*chosen_number3+chosen_number_4

That's the pattern you used with m1, and that would fix the error.

answered Nov 3, 2014 at 11:05

Warren Weckesser

116k20 gold badges207 silver badges224 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

DimKoim Over a year ago

It worked. Totally my mistake. Thanks. I think I should delete my post.

Warren Weckesser Over a year ago

It happens. If the problem was just a typographical error, then sure, it would make sense to delete the question.

Collectives™ on Stack Overflow

ValueError: NumPy boolean array indexing assignment cannot assign 0 input values to the N output values where the mask is true

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related