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From |
"Nick Cox" <n.j.cox@durham.ac.uk> |

To |
<statalist@hsphsun2.harvard.edu> |

Subject |
st: RE: Re: Storing output from a loop in only one variable |

Date |
Thu, 8 Jul 2010 17:30:22 +0100 |

A fairly general recipe is gen output = . local i = 1 foreach ... { ... replace output = ... in `i++' ... } su output The presumption is that you have enough observations for this to work. The `i++' uses the stored value of local macro i, then bumps it up. You asked why does ... in t not work, when -t- is a numeric variable. -replace- expects to see a literal number or numeric range as the argument of -in-. ... in `=t' would work as a contraction of `=t[1]' but using local macros as above is greatly preferable. It would work because the evaluation of `=t' takes place before -replace- sees the rest of the command line. On loops, see for example my namesake's articles SJ-3-2 pr0009 . . . . . . . . . . . . . Speaking Stata: Problems with lists . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . N. J. Cox Q2/03 SJ 3(2):185--202 (no commands) discusses ways of working through lists held in macros SJ-2-2 pr0005 . . . . . . Speaking Stata: How to face lists with fortitude . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . N. J. Cox Q2/02 SJ 2(2):202--222 (no commands) demonstrates the usefulness of for, foreach, forvalues, and local macros for interactive (non programming) tasks Nick n.j.cox@durham.ac.uk Dani Tilley Hi Eric, Thanks for your reply. Unfortunately, this doesn't give me what I'm looking for. With the correction you pointed below, I get an x variable that only has the output from the first loop on ALL its entries. I'm rather looking for a variable that has -a- entries (the output from each loop on each line) and -N-a- missing values. Incidentally, could anyone tell me why I'm getting this error: gen x=. gen int t=2 replace x=123 in t 't' invalid obs no r(198); what is a valid obs no apart from actual integers plugged in? If I can figure out a way to generate a variable that would not trigger this error, I can then replace var=var+i and solve the problem I have. Eric Booth Sorry, that should be "x", not "`x'" in the line: > replace x = `a' if !mi(`a') & mi(`x') From: Dani Tilley <tilleydani@yahoo.com> I'm trying to store certain output in a new variable while I loop through different categories. At the end I want to average what I've stored and perhaps do some other manipulations. Right now, my code looks like this: foreach a in {range} { ... gen x`a'={output} in 1 ... } su x*, mean di r(mean) drop x* So I create `a' variables that have the desired output as their 1st observations and N-1 missing points. I then average across these variables and drop them. While this gets the job done, I feel it's very clumsy. I'm looking to create a single variable, x, that will hold all `a' outputs. Something like scalar i=1 foreach a in {range} { ... gen x={output} in i i++ //or i=i+1 } * * 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/

**Follow-Ups**:**Re: st: RE: Re: Storing output from a loop in only one variable***From:*Dani Tilley <tilleydani@yahoo.com>

**References**:**st: Re: Storing output from a loop in only one variable***From:*Dani Tilley <tilleydani@yahoo.com>

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