Writing data on a single line using savetxt in Python-CodePudding

What I want to do, is basically convert this Fortran code into Python:

open (1,file='file',form='formatted')       
write (1,*) na,nb
write (1,*) (a(i),i=1,na) 
write (1,*) (b(j),j=1,nb)
do i=1,na
   write (1,*) (f1(i,j),j=1,nb)
   write (1,*) (f2(i,j),j=1,nb)
enddo

So I thought about using savetxt. The first difficulty I found, was the first line, where na and nb should be save on the same line in the file. I've found that you can achieve this with:

np.savetxt("file.txt",(na,nb),fmt='%s',newline=" ")

The problem, is then whenever I want to write the second line as:

f=open("file.txt",'f')
np.savetxt(f,a,fmt='%s',newline=" ")

The array a gets added on the same line as na and nb, while I want it to be so on a new one. I can't figure out how to do this. I thought that with newline=" ", I just had to add " " to na,nb, but it doesn't work. Alternatively, what would be the cleanest way to write that Fortran code?

CodePudding user response：

Assuming you one one row on each line like

1.23 1.23 1.23 1.23
2.34 2.34 2.34 2.34

then something like this should work:

f = open('file.txt','w')
print(na, nb, file=f)
np.savetxt(f, a.reshape(1,na), fmt='%s', delimiter=' ')
np.savetxt(f, b.reshape(1,nb), fmt='%s', delimiter=' ')
for row in range(f1.shape[0]):
  np.savetxt(f, f1[row], fmt='%s', delimiter=' ')
  np.savetxt(f, f2[row], fmt='%s', delimiter=' ')

savetxt puts one row on each line, but with a 1-D array, each element is considered a row. Thus, I reshape it to 2-D (reshape costs almost nothing; it just changes the interpretation).