Output array after performing fast fast fourier transform of a data set

Question

I'm trying to perform a fourier transform of a data set that I have and subsequently writing its real and imaginary parts separately.

This is my code:

import sys,string
import numpy as np
from math import *
import fileinput
from scipy.fftpack import fft, ifft

temparray = []

for i in range(200000):
    line = sys.stdin.readline() ## reads data from a text file
    fields = map(float,line.split())
    temparray.append(fields)
acf = sum(temparray,[]) ## I need to do this as the appended array from above is nested
y = np.fft.fft(acf)
z = (y.real,y.imag)
print z

The output that I get is as follows:

(array([ 2600.36368107, 2439.50426935, 1617.52631545, ..., 1575.78483016, 1617.52631545, 2439.50426935]), array([ 0. , -767.19967198, -743.75183367, ..., 726.45052092, 743.75183367, 767.19967198]))

It looks like its only printing the first few and last few values, completely skipping everything in between. Can anybody please tell me why this is happening?

Thanks

Are you just referring to the fact that numpy doesn't display the whole thing when you print it? That's done so that large arrays don't completely fill the output. There's a setting you can change, see here: http://stackoverflow.com/questions/1987694/print-the-full-numpy-array — Jezzamon, Feb 10 '16 at 23:47

score 2 · Accepted Answer · 2016-02-11T00:40:55.667

As others have indicated, include a modified version of

>>> np.set_printoptions(edgeitems=5,linewidth=80,precision=2,suppress=True,threshold=10) 
>>> a = np.arange(0,100.)
>>> 
>>> a
array([  0.,   1.,   2.,   3.,   4., ...,  95.,  96.,  97.,  98.,  99.])
>>> np.set_printoptions(edgeitems=5,linewidth=80,precision=2,suppress=True,threshold=100) 
>>> a
array([  0.,   1.,   2.,   3.,   4.,   5.,   6.,   7.,   8.,   9.,  10.,  11.,
        12.,  13.,  14.,  15.,  16.,  17.,  18.,  19.,  20.,  21.,  22.,  23.,
        24.,  25.,  26.,  27.,  28.,  29.,  30.,  31.,  32.,  33.,  34.,  35.,
        36.,  37.,  38.,  39.,  40.,  41.,  42.,  43.,  44.,  45.,  46.,  47.,
        48.,  49.,  50.,  51.,  52.,  53.,  54.,  55.,  56.,  57.,  58.,  59.,
        60.,  61.,  62.,  63.,  64.,  65.,  66.,  67.,  68.,  69.,  70.,  71.,
        72.,  73.,  74.,  75.,  76.,  77.,  78.,  79.,  80.,  81.,  82.,  83.,
        84.,  85.,  86.,  87.,  88.,  89.,  90.,  91.,  92.,  93.,  94.,  95.,
        96.,  97.,  98.,  99.])

np.set_printoptions(edgeitems=3,linewidth=80,precision=2,suppress=True,threshold=5)

perhaps setting threshold to some very large number.

Addendum

I would be remiss if I didn't state that the simplest solution to the above is to simple use

>>> list(a)

should you not care whether an array is visually returned or not.

Output array after performing fast fast fourier transform of a data set

1 Answers1