visualize_diff.py

import difflib

def visualize_diff(a, b):
    seqm = difflib.SequenceMatcher(None, a, b)
    output= []
    for opcode, a0, a1, b0, b1 in seqm.get_opcodes():
        if opcode == 'equal':
            output.append(seqm.a[a0:a1])
        elif opcode == 'insert':
            output.append(green)
            output.append(seqm.b[b0:b1])
            output.append(default)            
        elif opcode == 'delete':
            output.append(red)            
            output.append(seqm.a[a0:a1])
            output.append(default)
        elif opcode == 'replace':
            output.append(b_green)            
            output.append(seqm.b[a0:a1])
            output.append(b_red)            
            output.append(seqm.a[a0:a1])            
            output.append(default)
        else:
            raise RuntimeError
    return output