Python 3.8 : How to split information nicely

I have a log file which contains these information :

- TEST B1

B1_D<4.9b(8.9,9.25)B

B1_D=16.9b(15.9,17.25)B

H32_DOT_FAT<4.9H(5.9,7.25)H

 H32_DOT_FBAT<4.9H(5.9,7.25)H

R31=1.5K(1.45K,1.54K)R 

R33=3.8K(3.62K,4.17K)R

I want to parse this file like as below :

Legend

SCN : first line
STEP : first part of split for "_" seperator
CHILD : the rest of split  for "_" seperator
MESURE_CHILD : the rest of split for "=" separator or " < "

Output Expected :

SCN = TEST B1 
STEP = B1
CHILD = D
MESURE_CHILD : 4.9b(8.9,9.25)B
CHILD : D
MESURE_CHILD : 16.9b(15.9,17.25)B
STEP = H32
CHILD = DOT_FAT
MESURE_CHILD : 4.9H(5.9,7.25)H
CHILD : DOT_FBAT
MESURE_CHILD : 4.9H(5.9,7.25)H
STEP = R31
CHILD : R31
MESURE_CHILD : 1.5K(1.45K,1.54K)R
STEP = R33
CHILD : R33
MESURE_CHILD : 3.8K(3.62K,4.17K)R

I use python 3.8 to coding. You find as below method that i used but i don't find the solution nicely

def createTreeStandardBloc(self, data_bloc):

    index_bloc = 1
    data = data_bloc[ 0 ]
    if ( "=" in data [ index_bloc ] or "<" in data [ index_bloc ] ) :
        prefix = re.split(r'(<|=)\s*', data [ index_bloc ] )[ 0 ]
        if ( "_" in prefix ):
            step_name = re.split( "_" , prefix )[ 0 ]
        else:
            step_name = prefix

    print("STEP : "+step_name)
    for index_bloc in range( 2 , len( data ) ) :
        if ( "=" in data [ index_bloc ] or "<" in data [ index_bloc ] ) :
            prefix_pdm = re.split(r'(<|=)\s*', data [ index_bloc ] )[ 0 ]
            if ( "_" in prefix_pdm ):
                step_name_temp = re.split( "_" , prefix_pdm ) [ 0 ]
                pdm            = re.split( "_" , prefix_pdm ) [ 1 ]
            else:
                step_name_temp = prefix_pdm
                pdm            = prefix_pdm                   

        if ( step_name_temp != step_name ):
            step_name = step_name_temp
            print("STEP : "+step_name)
            print("CHILD : "+pdm)

        else :
            print("CHILD : "+pdm)

Solution

You can use a regular expression for getting the parts from the lines:

import re
last_s = None
for i, line in enumerate(data.splitlines()):
    if i == 0:
        print("SCN:", line.strip("- "))
    elif line.strip():
        s, c, mc = re.match("^\s*([^_]+)(_\w+)?[<>=](.*)\s*$", line).groups()
        if s != last_s:
            print("STEP", s)
        print("CHILD", c or s)
        print("MEASURE_CHILD", mc)
        last_s = s

Let's break this down a bit:

^\s* -- start of line, possibly whitespace
([^_]+) -- some non-underscore chars (1st group)
(_\w+)? -- underscore, then more characters (2nd group)
[<>=](.*) -- comparison, more stuff (3rd group)
\s*$ -- optional whitespace, then end of line