st: Finding matching strings across vars

[Steve Nakoneshny <scnakone@ucalgary.ca>]

Dear Statalist,

A colleague has provided me with an excel file of 3 vars and 43,510 obs of gene names (all strings, all uppercase). Each var represents a different list of genes and he has asked me if there is an "easy" way in Stata to find out if any of the genes listed in var1 also appear in var2 and/or var3. To further complicate matters, the obs in var1 are non-unique and many have multiple alternate gene names like "ANKRD20A13P///ANKRD20A4///ANKRD20A2///ANKRD20A3///ANKRD20A11P///ANKRD20A9P///ANKRD20A1" embedded into the same obs.

In visualising a plan of attack, I'm thinking I need to read in var1, drop duplicates, split the longer obs parsing on "///", reshape long and drop duplicate once again to arrive at a single var list of unique gene names. This next step is where my plan starts to break down. I'm leaning towards appending the excel file again to read in var2 and var3, but then I'm not 100% sure on how to search for matches across each var or how to readily identify them once I do.

Any comments or suggestions would be greatly appreciated.

Steve

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