How to sift through data and only keep the rows with the value I need

[Anqi Zhang]

Hi everyone.

Please see the attached sample data. I would like to keep all the rows for any cell value in column cat1, or cat2, or cat3 that start with "F".

Appreciate it if you could give me some suggestions and guidance.

Thank you.

[William Lisowski]

Perhaps

keep if substr(cat1,1,1)=="F" | substr(cat2,1,1)=="F" | substr(cat3,1,1)=="F"

[Anqi Zhang]

Perhaps

keep if substr(cat1,1,1)=="F" | substr(cat2,1,1)=="F" | substr(cat3,1,1)=="F"

Thank you Dr. Lisowski.

If I have many columns, dozens of them, instead of three as shown here. Is there a way to group them first instead of using many "|" syntax?

Thank you again.

[William Lisowski]

generate tokeep = 0
foreach v in varlist cat1 cat2 cat3 {
    replace tokeep = 1 if substr(`v',1,1)=="F"
}
keep if tokeep

See the output of help varlist for examples of ways to concisely list dozens of variable names.