Find row number for specific change in python numpy

Question

I have a file like this:

C
C
C
C
C
C
C
C
B
C
C
C
C
C
C
C
C
C         
C        
C         
C        
C       
C
C            
C
C
B   
B   
B
B   
B   

I like to print the row number where there is a change from C to B. Like here in row 9 and 27. I need to row number only. How to do that in numpy python.

Thank you

Answer 1

This is one possible solution, but it's not using Numpy

f = open('yourfile.txt', 'r')
x = 0
for i in f:
   x = x + 1
   if i == 'B':
      print('row' + str(x))