Re: st: Replace one variable when other variable contains certaincharacters

[Joseph Coveney <jcoveney@bigplanet.com>]

FUKUGAWA Nobuya wrote:

Suppose we have string variable Y, and we would like to replace
variable X when variable Y contains certain characters such as
"Dec".
In other words, we want to write;
replace X="m12" if Y (contains "Dec")
replace X="m11" if Y (contains "Nov")
replace X="m10" if Y (contains "Oct") .
How can I write the latter part of command?
Please note Y can be Dec123abc, 456Novpqr, and zzz789Oct.

--------------------------------------------------------------------------------

Rafal Raciborski responded with an answer that uses Stata's new regular
expression functions.  If you have an earlier release, then:

replace X = "m12" if index(Y, "Dec")
replace X = "m11" if index(Y, "Nov")
replace X = "m10" if index(Y, "Oct")

Note that in Stata 9, you can use -strpos()- instead of -index()-:

replace X = "m12" if strpos(Y, "Dec")
replace X = "m11" if strpos(Y, "Nov")
replace X = "m10" if strpos(Y, "Oct")

You can get cute, too, if you want to:

foreach month in `c(Mons)' {
    replace X = "m" + ///
      string(month(date("2000-`month'-01", "ymd")), "%02.0f") ///
      if strpos(Y, "`month")
}

This last snippet helps avoid tedium if you need to replace X for all twelve 
months, but would be overkill for just three.

Joseph Coveney

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