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From |
Nick Cox <njcoxstata@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: Need Help Recoding a variable -Dealing with string expression |

Date |
Thu, 21 Jun 2012 08:28:28 +0100 |

Stata's own -search- command (recommended in the Statalist FAQ) with the text -regular expressions- answers your second question. Among other sources, it points to FAQ . . . . . . . . . . . . . . . . . . . . . . . . . Regular expressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . K. S. Turner 10/05 What are regular expressions and how can I use them in Stata? http://www.stata.com/support/faqs/data/regex.html FAQ . How to extract a portion of a string var. using regular expressions? . . . . . . . . . . . . . . . . . . UCLA Academic Technology Services 7/08 http://www.ats.ucla.edu/stat/stata/faq/regex.htm Your first question is less clear to me, but have a look at FAQ . . . . . . . . . . . . . . . . . . . . . . . True and false in Stata . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . N. J. Cox 2/03 What is true and false in Stata? http://www.stata.com/support/faqs/data/trueorfalse.html The syntax recommended was based on a short-cut, the fact that if strpos(strvar, "<") > 0 and if strpos(strvar, "<") _in this kind of problem_ are treated in the same way. The FAQ spells out why, but in a clause: in any context where Stata needs the answer to a true or false question, non-zero is treated as true and only zero is treated as false. Nick On Thu, Jun 21, 2012 at 3:29 AM, Michael Stewart <michaelstewartresearch@gmail.com> wrote: > Dear Nick, > > I have executed the stata command per your suggestions and worked > exactly as I wanted. > I became more interested in the string functions and started reading > up on them in stata pdf manual but got lost . > Can you please help me understand the logic here > strpos(strvar,">")--> supposed to return position where > is found and > if > is not found to return a value zero but we are able to combine > the strpos function with replace and even if > is found , we are able > to convert the misisng value to zero .Can you please explain the logic > here. > > Also would you recommend any good reference for using / building the > regular expressions. > Thanks a lot Nick for your time > > -- > Thank you , > Yours Sincerely, > Mike. > > > > On Wed, Jun 20, 2012 at 1:47 PM, Nick Cox <njcoxstata@gmail.com> wrote: >> Same answer, really. Something like >> >> destring strvar, gen(numvar) force >> >> replace numvar = 3 if strpos(strvar, ">") | strpos(strvar, "<") | >> regexm(strvar, "[a-z]+") >> >> You need to find out about string functions. -help functions-. >> >> Nick >> >> On Wed, Jun 20, 2012 at 4:52 PM, Michael Stewart >> <michaelstewartresearch@gmail.com> wrote: >>> Thank you Nick and Daniel . >>> >>> I am sorry that my post want clear enough. >>> >>> Once I destring, with a force option, I get some missing values >>> corresponding to non numeric vaulues. >>> >>> I wanted to recode the missing values in the new variable to number 3 >>> if there is an alphabet(could be anything from a to z) or a symbol (< >>> or > ) in the corresponding observation for the original variable >>> like "sometimes" "< two" "<3" ">5 " "<0.5" ">four" . >> >> >> On Wed, Jun 20, 2012 at 10:00 AM, Nick Cox <njcoxstata@gmail.com> wrote: >> >>>> The question is too general to answer fully but one pattern is just >>>> >>>> recode x <whatever> if y == "foo" >>>> >>>> In addition to exact equality of string values there are many other >>>> possibilities involving string functions. >> >> On Wed, Jun 20, 2012 at 2:49 PM, Michael Stewart >> >>>>> I need to recode a variable if another variable has a nonnumeric >>>>> string observation(could have any non-numeric expression) >>>>> >>>>> Eg: recode x(......) if y =TSTATA COMMAND (any non-numeric >>>>> string expression) >>>>> >>>>> Can you please help me with the command to take into consideraiton >>>>> "any non-numeric string expression " * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**References**:**st: Need Help Recoding a variable -Dealing with string expression***From:*Michael Stewart <michaelstewartresearch@gmail.com>

**Re: st: Need Help Recoding a variable -Dealing with string expression***From:*Nick Cox <njcoxstata@gmail.com>

**Re: st: Need Help Recoding a variable -Dealing with string expression***From:*Michael Stewart <michaelstewartresearch@gmail.com>

**Re: st: Need Help Recoding a variable -Dealing with string expression***From:*Nick Cox <njcoxstata@gmail.com>

**Re: st: Need Help Recoding a variable -Dealing with string expression***From:*Michael Stewart <michaelstewartresearch@gmail.com>

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