I have a dataframe like below, and would like to fill value from previous row value based on id field, so, any record with 4 in colA get what the previous colA=3 records' colC value, colB stays the same. I've tried ffill, and shift, but couldn't get what I want, please help. Thank you. colA colB colC 3 air 00JTHYU1 4 ground 00JTHYU0 4 ground 00JTHYU0 4 ground 00JTHYU0 3 air 00JTHYU4 4 ground 00JTHYU0 4 air 00JTHYU0 3 ground 00JTHYU7 4 ground 00JTHYU0 Result: colA colB colC 3 air 00JTHYU1 4 ground 00JTHYU1 4 ground 00JTHYU1 4 ground 00JTHYU1 3 air 00JTHYU4 4 ground 00JTHYU4 4 air 00JTHYU4 3 ground 00JTHYU7 4 ground 00JTHYU7 Continue reading...
