Specific Column Widths And Alignment With Savetxt

I'm nearly finished with this program, but I can't get the output quite how I want it. Here is the code: import numpy as np filename = (raw_input('Which file are we loading? '))

Solution 1:

You can make different formats for each column by passing a sequence to the 'fmt' keyword argument. Three examples below show different options. More info available at docs.scipy.org.

>>>import numpy as np>>>a = np.random.random((3,4))>>>a[1] = a[1] + 10>>>a
array([[  0.66860114,   0.29021582,   0.47168711,   0.86839242],
       [ 10.41030497,  10.22771623,  10.80389801,  10.6170771 ],
       [  0.47201727,   0.90861352,   0.03952651,   0.67245859]])
>>>>>># saved using string format>>>>>>np.savetxt('string.txt', a, fmt='%s')>>>withopen('string.txt','r') as f: print(f.read())...
0.668601144977 0.290215822112 0.471687110847 0.86839242197
10.4103049716 10.2277162318 10.8038980106 10.617077099
0.472017270547 0.9086135154 0.0395265080276 0.672458588797
>>>>>># saved using floating format with the "width" parameter = 10>>>>>>np.savetxt('fixed.txt',a, fmt='%10.4f')>>>withopen('fixed.txt','r') as f: print(f.read())...
    0.6686     0.2902     0.4717     0.8684
   10.4103    10.2277    10.8039    10.6171
    0.4720     0.9086     0.0395     0.6725
>>>>>># saved using format specifier sequence with format for each column>>>>>>np.savetxt('multi.txt',a, fmt=('%5.2f', '%10.4f', '%7.3f', '%12.1f'))>>>withopen('multi.txt','r') as f: print(f.read())... 
 0.67     0.2902   0.472          0.9
10.41    10.2277  10.804         10.6
 0.47     0.9086   0.040          0.7

Solution 2:

What you want to achieve is a so called 'fixed-width' csv-file. Since neither numpy nor pandas is able to export data to a csv-file formatted like this you could do a workaround using the format specifier of numpy.savetext() if you know the number of digits you have to handle:

#!/usr/bin/env python3# coding: utf-8import numpy as np

# generate a random array to get some sample data
newlist = np.random.rand(3,2)

# assume you have three decimal digits and seven in total (so four in front of the decimal sign)
np.savetxt('observe.list', newlist, fmt='%7.3f')

Giving:

  0.021   0.571
  0.471   0.416
  0.177   0.720

---

Update due to comment:

newlist = np.array([1.5, 10.55555, 0.3, 2, 5.0])
np.savetxt('observe.list', newlist, fmt='%10.5f')

Giving:

   1.50000
  10.55555
   0.30000
   2.00000
   5.00000