This is my data frame attached in image and I want to sum as per the first column where ?? represent no value for that entry DATAFRAME IMAGE SAMPLE I want to write code to have an output like below HWK 0 CSP 0 DCF 0 I want to sum the values only if n/a or ?? occurs then ignore it and do the sum so that I can iterate through all the data frame for the same procedure
HWK      0 
CSP     ?? 
DCF      0 
BM_IO   ?? 
CS      ?? 
os      ?? 
CS       0 
ESC      0 
ESC      0 
DCF      0 
DLHLTL  ?? 
CSP      0 
CSP      0 
ESC      0 
CSP     ??
 
     
    