Pretty-printing of numpy.array

Question

Hello,

I'm curious, whether there is any way to print formated numpy.arrays, e.g., in the way similar to this:

x = 1.23456
print '%.3f' % x

If I want to print the numpy.array of floats, it prints several decimals, often in 'scientific' format, which is rather hard to read even for low-dimensional arrays. However, numpy.array apparently has to be printed as a string, i.e., with %s. Is there any solution ready for this purpose? Many thanks in advance :-)

Answer 1

You can use set_printoptions to set the precision of the output:

import numpy as np
x=np.random.random(10)
print(x)
# [ 0.07837821  0.48002108  0.41274116  0.82993414  0.77610352  0.1023732
#   0.51303098  0.4617183   0.33487207  0.71162095]

np.set_printoptions(precision=3)
print(x)
# [ 0.078  0.48   0.413  0.83   0.776  0.102  0.513  0.462  0.335  0.712]

And suppress suppresses the use of scientific notation for small numbers:

y=np.array([1.5e-10,1.5,1500])
print(y)
# [  1.500e-10   1.500e+00   1.500e+03]
np.set_printoptions(suppress=True)
print(y)
# [    0.      1.5  1500. ]

See the docs for set_printoptions for other options.