IndexError: index 1 is out of bounds for axis 0 with size 1 (Python, NumPy)

Question

I am using for loops to iterate through the indices in a NumPy zeros array and assign some indices with the value 0.5. At the moment, my code returns the error message:

IndexError: index 1 is out of bounds for axis 0 with size 1

Below is a simplified version of my code which reproduces the error.

import numpy as np

Z = np.zeros((1560, 1560))
linestart = {1: [175], 2: [865]}
noycuts = 2

cutno = int(0)
for i in range(noycuts):
    cutno = cutno + 1
    xstart = linestart[cutno]
    ystart = 0
    for j in range(1560):
        Z[xstart][ystart] = 0.5
        ystart = ystart + 1

I've checked questions from people with the same error code, although these issues seem to stem from how the array was originally called; I don't think this is my problem.

Can anyone see the flaw in my code that is causing the error message?

I hope I have provided enough information.

Thanks in advance.

It did originally, although I changed it to 1 to see if it made any difference and I've forgotten to change it back. I've edited it back to 0. Thanks. — C. Pugh
– C. Pugh, Commented Jan 30, 2017 at 14:32

elzell · Accepted Answer · 2017-01-30 14:39:26Z

1

Edit:

My original answer was:

Replace

Z[xstart][ystart] = 0.5

with

Z[xstart, ystart] = 0.5

But actually, the problem is, that your xstart is an array. Leave your original code, but replace

linestart = {1: [175], 2: [865]}

with

linestart = {1: 175, 2: 865}

or, better:

linestart = [175, 865]

edited Jan 30, 2017 at 14:39

answered Jan 30, 2017 at 14:32

elzell

2,3362 gold badges19 silver badges28 bronze badges

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

1 Comment

C. Pugh Over a year ago

Thank you very much. I thought it would be something simple! Could you possibly explain why this works? I have for loops earlier in the code using the "Z[xstart][ystart]" syntax and these work perfectly fine.

Jul3k · Accepted Answer · 2017-01-30 14:46:32Z

0

With linestart = {1: [175], 2: [865]} you define a dict containing lists with single entrys. I belive you actually want the dict to contain ints. Also ystart should start with zero. Does the following do what you want:

import numpy as np

Z = np.zeros((1560, 1560))
linestart = {1: 175, 2: 865}
noycuts = 2

cutno = 0
for i in range(noycuts):
    cutno += 1
    xstart = linestart[cutno]
    ystart = 0
    for j in range(1560):
        Z[xstart][ystart] = 0.5
        ystart = ystart + 1

Also consider the following which is a shorter version:

for cutno,xstart in linestart.items():
    for ystart in range(Z.shape[1]):
        Z[xstart][ystart] = 0.5

edited Jan 30, 2017 at 14:46

answered Jan 30, 2017 at 14:38

Jul3k

1,1061 gold badge10 silver badges19 bronze badges

2 Comments

C. Pugh Over a year ago

Yes this does exactly what I want. In this particular instance the dict contains only single entries per key, however, in the full code, I have multiple dicts which are added to via raw_input and sometimes contain more than one entry per key; these dicts require the use of lists and I have sloppily continued to use the same format for this dictionary also. Thank you for pointing this out.

C. Pugh Over a year ago

Also, thanks for the shorter version, it's very helpful.

Collectives™ on Stack Overflow

IndexError: index 1 is out of bounds for axis 0 with size 1 (Python, NumPy)

2 Answers 2

1 Comment

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related