Storing two values in an array python

Question

Hi im sure there is a much more efficient way of coding this, im primarily a java programmer but trying to help some one out with some basic python.

I need to have a 2D array which contains a set of random co-ordinates eg (2, 10). My initial thought was to create the array then fill it will smaller arrays containing the two co-ordinates.

import numpy
import random

a = numpy.zeros(10000).reshape(100, 100)
temp = []
for i in range(0,100):
    for j in range(0,100):
        temp.append(random.randint(0,100))
        temp.append(random.randint(0,100))
        a[i][j]=temp

print a

This produces the error ValueError: setting an array element with a sequence.

So whats the best way to go about solving this problem? Sorry for this hacked together code i've never really had to use python before!

HYRY · Accepted Answer · 2013-03-28 12:02:23Z

2

That is a three dim array, you can create it by:

np.random.randint(0, 100, (100, 100, 2))

answered Mar 28, 2013 at 12:02

HYRY

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3 Comments

user2219545 Over a year ago

will that create a 100 * 100 array with the co ordinates ?

Janne Karila Over a year ago

@user2219545 That's a 100 * 100 * 2 array, where the two coordinates use the last dimension.

pradyunsg Over a year ago

@user2219545 Janne means to say Yes!.

Hal Canary · Accepted Answer · 2013-03-28 12:22:41Z

0

import numpy
import random
a = numpy.zeros((100, 100, 2))
for i in range(0,100):
    for j in range(0,100):
        a[i,j,:] = (random.randint(0,100),
                    random.randint(0,100))
print 'x-coords:\n', a[:,:,0]
print 'y-coords:\n', a[:,:,1]

answered Mar 28, 2013 at 12:22

Hal Canary

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Comments

dermen · Accepted Answer · 2013-03-30 00:27:18Z

0

@HYRY gives the correct answer if I understand what you are trying to do.. The reason you get a Value error is because you are assigning a sequence, or python list (tmp) to a single float ( a[i][j] ). @HalCanary shows you how to do fix your code to get around this error, but HYRY's code should be optimal for python computing.

answered Mar 30, 2013 at 0:27

dermen

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