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

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

Subject |
RE: st: string functions on the name of a variable |

Date |
Mon, 21 Nov 2005 11:14:30 -0000 |

I don't see that you need a function here. The set of variables with "clli" as part of their names is given by the wildcard *clli* and so can be put into a macro by unab clli : *clli* Presumably you know what variables appear on the RHS of your regression and can manufacture a local macro containing them, say rhs. The intersection is then local cllirhs : list clli & rhs and you can cycle over these with foreach v of local cllirhs { ... = ... + _b[`v'] } Assuming that by Fourrier you mean Fourier, I don't see why handling a set of Fourier terms need be messy. The utility -fourier- from -circular- on SSC provides one way of getting a bunch of them. Alternatively, in one recent program I needed to generate a bunch of them on the fly. Here is the code generalised mildly: // regression in terms of sin j theta, cos j theta local sc local terms = <plug in your own> forval j = 1/`terms' { tempvar S C gen `S' = sin(`j' * `theta') gen `C' = cos(`j' * `theta') local sc `sc' `S' `C' } // regression will fail if data points too few // or response missing // assumes a `touse' marking observations to be used capture regress <response to be plugged in> `sc' if `touse' if _rc gen `sm' = . if `touse' else predict `sm' if `touse' drop `sc' On the other hand, quite what a "Flexible" Fourier analysis is I don't know. Nick n.j.cox@durham.ac.uk Dev Vencappa > I have the following problem and would be grateful if you > could provide some help: > > Suppose I have a regression equation with lntoen as my > dependent variable and a lot of right hand side variables > called lncllisqr lncllica lncllite lncaclli (and there are > more variables like these which contain the word "clli" in > their name as well as other variables named differently). > After estimation, I am trying to add the coefficients of all > variables in an estimation that have "clli" in their names. > While I can do this manually by using _b[variablename], I am > faced with a problem as I am estimating a Flexible Fourrier > function, which tends to be very messy in terms of the > addition of trigonometric terms. > > I am trying to differentiate lntoen with respect to all > variables that contain "clli" in their names. I am trying to > automate this process by asking stata to add the coefficients > of all variables that contain "clli" in their names. > > Does anybody know if there is an equivalent to one of the > list of string functions (such as e.g. substr) that can allow > me to write some condition to check if the variable contains > the characters "clli" in its name and then add their > coefficients please? > > Apologies if a similar posting has been up on the list before > and escaped my attention. * * For searches and help try: * http://www.stata.com/support/faqs/res/findit.html * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

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