Python：返回循环结果时出错

Question

My output for the following code is only save the last row of result instead of putting every single row of values into the csv file. I have limited knowledge in python. I think my looping part is incorrect. Can anyone help me?

Code

import numpy as np
from numpy import genfromtxt

with open('binary.csv') as actg:
    actg=actg.readlines()
    with open('single.csv') as single:
        single=single.readlines()
        with open('division.csv') as division:
            division=division.readlines()

            for line in actg:
                for line2 in single:
                    for line1 in division:

                        myarray = np.fromstring(line, dtype=float, sep=',')
                        myarray = myarray.reshape((-1, 3, 4))
                        a=np.asmatrix(myarray)
                        a=np.array(a)

                        single1 = np.fromstring(line2, dtype=float, sep=',')
                        single1 = single1.reshape((-1, 4))
                        s=np.asmatrix(single1)
                        s=np.array(s)

                        division1 = np.fromstring(line1, dtype=float, sep=',')
                        m=np.asmatrix(division1)
                        m=np.array(m)
                        res2 = (s[np.newaxis,:,:] / m[:,np.newaxis,:] * a).sum(axis=-1)

np.savetxt("output.csv", res2, delimiter=",")

binary.csv

0,1,0,0,1,0,0,0,0,0,0,1
0,0,1,0,1,0,0,0,1,0,0,0

single.csv:

0.28,0.22,0.23,0.27,0.12,0.29,0.34,0.21,0.44,0.56,0.51,0.65

division.csv

0.4,0.5,0.7,0.1
0.2,0.8,0.9,0.3

Expected output

 0.44,0.3,6.5
 0.26,0.6,2.2

Actual output

0.26,0.6,2.2

Answer 1

It is not you python understanding. It is your loop logic understanding.

If you look closely at your loops, you (and not Python) always keep the last elements.

In the first and second loops you overwrite each time the variable that you need and you do not keep the overall information for each iteration.

In the last loop, you declare the row variable as new list in each iteration.

Also, the i variable is not set up anywhere except as the index variable in the for loop!

Answer 2

Because of the fact that you only write out the results after the loops have finished, you are only seeing the last result.
Also, I would expect 4 results from that data, not 2.
You need to write the output on each iteration or store each iteration and then write out the stored values.
Try printing res2 each time you calculate it and you will see something like this:

('Final Results', array([[ 0.44,  0.3 ,  6.5 ]]))
('Final Results', array([[ 0.275     ,  0.6       ,  2.16666667]]))
('Final Results', array([[ 0.32857143,  0.3       ,  1.1       ]]))
('Final Results', array([[ 0.25555556,  0.6       ,  2.2       ]]))