我需要一种方法来摆脱 numpy 数组中的大括号

Question

I have a 61-by-61 matrix (numpy array) that includes double values (complex numbers). I want to save my matrix as a CSV file, then use it in Matlab. But all the elements have curly brackets "(, )". For example, an element is like:

 (3.2-0.4j) 

I want all my elements to be without curly brackets; I mean:

3.2-0.4j

Answer 1

In [213]: arr = np.arange(3.)+np.arange(4)[:,None]*1j                                   
In [214]: arr                                                                           
Out[214]: 
array([[0.+0.j, 1.+0.j, 2.+0.j],
       [0.+1.j, 1.+1.j, 2.+1.j],
       [0.+2.j, 1.+2.j, 2.+2.j],
       [0.+3.j, 1.+3.j, 2.+3.j]])

How you attempted it (probably):

In [220]: np.savetxt('test.txt',arr, delimiter=',', fmt='%3d')                          
In [221]: cat test.txt                                                                  
 (  0+  0j), (  1+  0j), (  2+  0j)
 (  0+  1j), (  1+  1j), (  2+  1j)
 (  0+  2j), (  1+  2j), (  2+  2j)
 (  0+  3j), (  1+  3j), (  2+  3j)

With the complex format as suggested in the docs (an exact copy):

In [223]: np.savetxt('test.txt',arr, fmt=' %.4e %+.4ej %.4e %+.4ej %.4e %+.4ej')   
                                                                
In [224]: cat test.txt                                                                  
 0.0000e+00 +0.0000e+00j 1.0000e+00 +0.0000e+00j 2.0000e+00 +0.0000e+00j
 0.0000e+00 +1.0000e+00j 1.0000e+00 +1.0000e+00j 2.0000e+00 +1.0000e+00j
 0.0000e+00 +2.0000e+00j 1.0000e+00 +2.0000e+00j 2.0000e+00 +2.0000e+00j
 0.0000e+00 +3.0000e+00j 1.0000e+00 +3.0000e+00j 2.0000e+00 +3.0000e+00j