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From |
Maarten Buis <maartenlbuis@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: Getting all independent vars from a set of reg equations |

Date |
Mon, 27 Jun 2011 13:06:51 +0200 |

On Mon, Jun 27, 2011 at 11:08 AM, Narahari H.S. wrote: > However, I have a large number of independent variables and their total no. of characters exceeds 244 - thus resulting in a truncation. How do I tackle this? In the code I sent I deliberately did _not_ say anything like -local x = ...- but always -local x ...- or -local x : ...-. The 244 character limit for strings does not bite as long as you do not evaluate your macros (i.e. as long as you leave the =-sign out) . See among others: Nicholas J. Cox (2008) "Stata tip 70: Beware the evaluating equal sign" The Stata Journal, 8(4): 586-587. > Also, among the independent variables, I have dummy variables for years which are named with a "y" prefix (like y2000, y2005 etc.). Is there any way to drop these variables? (I was hoping for a -drop y*- command similar to -list uniq- but thats not available) There are many nice tricks for manipulating lists in this way in the extended macro function, see -help macro- and click on the link for extended macro functions. On top of that you will want to expand a variable list and store the expanded list in (another) macro. This you can do with -unab-. The example below combines these two in order to exclude such a set of dummy/indicator variables. *---------------- begin example ----------------------- sysuse auto, clear // generate dummies tab rep78, gen(rep) // exclude reference category drop rep1 reg price mpg foreign indeplist local x = r(X) reg price mpg rep? foreign indeplist local x "`x' `r(X)'" reg price mpg rep? foreign gear_ratio indeplist local x "`x' `r(X)'" di "`x'" local x : list uniq x di "`x'" // get names of the dummies unab dummies : rep? di "`dummies'" // remove dummies from x local x : list x - dummies di "`x'" *------------------ end example ---------------------- (For more on examples I sent to the Statalist see: http://www.maartenbuis.nl/example_faq ) Hope this helps, Maarten -------------------------- Maarten L. Buis Institut fuer Soziologie Universitaet Tuebingen Wilhelmstrasse 36 72074 Tuebingen Germany http://www.maartenbuis.nl -------------------------- * * 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: Getting all independent vars from a set of reg equations***From:*Maarten Buis <maartenlbuis@gmail.com>

**References**:**Re: st: Getting all independent vars from a set of reg equations***From:*"Narahari H.S." <naraharihs@yahoo.co.in>

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