6

I have some data as numpy 2D array list- 

array([[ 0.62367947],
       [ 0.95427859],
       [ 0.97984112],
       [ 0.7025228 ],
       [ 0.86436385],
       [ 0.71010739],
       [ 0.98748138],
       [ 0.75198057]])

array([[-1.,  1., -1.],    
       [-1.,  1.,  1.],
       [ 1.,  1.,  1.],
       [ 1., -1.,  1.],
       [-1., -1., -1.],
       [ 1.,  1., -1.],
       [ 1., -1., -1.],
       [-1., -1.,  1.]])

And I want to save them in a txt file so that they look like 

0.62367947    -1 1 -1    
0.95427859    -1 1 1    
0.97984112     1 1 1

Can someone help me how I can do it using numpy savetxt

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2
  • 1
    What error are you getting? Commented May 1, 2013 at 12:11
  • Can you include the line where you actually use savetxt? Commented May 1, 2013 at 12:13

1 Answer 1

Reset to default
6 
import numpy as np
R = np.array([[0.62367947],
              [0.95427859],
              [0.97984112],
              [0.7025228],
              [0.86436385],
              [0.71010739],
              [0.98748138],
              [0.75198057]])

phase = np.array([[-1., 1., -1.],
                  [-1., 1., 1.],
                  [1., 1., 1.],
                  [1., -1., 1.],
                  [-1., -1., -1.],
                  [1., 1., -1.],
                  [1., -1., -1.],
                  [-1., -1., 1.]])

np.savetxt('R2.txt', np.hstack([R, phase]), fmt=['%0.8f','%g','%g','%g'])

yields

0.62367947 -1 1 -1
0.95427859 -1 1 1
0.97984112 1 1 1
0.70252280 1 -1 1
0.86436385 -1 -1 -1
0.71010739 1 1 -1
0.98748138 1 -1 -1
0.75198057 -1 -1 1

np.hstack stacks arrays horizontally. Since R and phase are both 2-dimensional, np.hstack([R, phase]) yields

In [137]: np.hstack([R,phase])
Out[137]: 
array([[ 0.62367947, -1.        ,  1.        , -1.        ],
       [ 0.95427859, -1.        ,  1.        ,  1.        ],
       [ 0.97984112,  1.        ,  1.        ,  1.        ],
       [ 0.7025228 ,  1.        , -1.        ,  1.        ],
       [ 0.86436385, -1.        , -1.        , -1.        ],
       [ 0.71010739,  1.        ,  1.        , -1.        ],
       [ 0.98748138,  1.        , -1.        , -1.        ],
       [ 0.75198057, -1.        , -1.        ,  1.        ]])

Passing this 2D array to np.savetxt gives you the desired result.

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5 Comments

@ unutbu - well, the answer you gave is working for one set of R2 and phase value. But I have 8 sets of R2 and phase values. And I have to use the append to have them in a list. So then when I am trying to save them using your code- it says- array dimensions must agree except for d_0
Collect all your R2 and phase values into a 2-dimensional array. Then call np.savetxt once for the entire 2D array.
array([[ 0.62367947], [ 0.95427859], [ 0.97984112], [ 0.7025228 ], [ 0.86436385], [ 0.71010739], [ 0.98748138], [ 0.75198057]]) array([[-1., 1., -1.], [-1., 1., 1.], [ 1., 1., 1.], [ 1., -1., 1.], [-1., -1., -1.], [ 1., 1., -1.], [ 1., -1., -1.], [-1., -1., 1.]]) I made them 2D arrays. Still I got the same error msg. pls have a look.
Please edit your original post with the code you are using to generate these arrays, how you are calling np.savetxt, and what you want the output to look like. I appreciate that you posted runnable code, but it would be nice if you pared it down to just the relevant part.
thanx for your explanation. Now I understand well and it is according to my result.

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