Hi All, Its a bit of a beginners question I'm afraid. I have a looped stepwise regression (using MASS and StepAIC) to take random predictors out of the total number. For this example a random sample of 5 out of a total of 20. The loop will continue until all combinations of variables have been run through the loop. The output from each loop can be derived from taking the significant (p) coefficients from the summary command, and coding them '1' (if <0.05) or '0' (if >0.05), and producing a table of 5 columns for each of the predictors entered. The table produced in the loop is much smaller than the input table. Is there a way to produce a results table using the original column titles of the input table which can be matched to the subset predictors table, where if the variable was not in the subset its row value is 'NA'? I hope that makes sense. Cheers In advance, Matt -- View this message in context: http://r.789695.n4.nabble.com/Adding-rows-to-a-table-with-a-loop-tp3933634p3933634.html Sent from the R help mailing list archive at Nabble.com.
Adding rows to a table with a loop
3 messages · Weidong Gu, MJS
It surely can be done. One way is to keep track of selected variables in a set. If a new variable is selected, you expand the selected set and set the frequency to be one, otherwise just increase the freqency of the selected variable (if... else). Also, you might want to have a look at glmulti package which conducts model selection out of all potential combinations, even including interactions if you don't have many variables. HTH Weidong Gu
On Mon, Oct 24, 2011 at 11:58 AM, MJS <taranis.1986 at gmail.com> wrote:
Hi All, Its a bit of a beginners question I'm afraid. I have a looped stepwise regression (using MASS and StepAIC) to take random predictors out of the total number. ?For this example a random sample of 5 out of a total of 20. ?The loop will continue until all combinations of variables have been run through the loop. The output from each loop can be derived from taking the significant (p) coefficients from the summary command, and coding them '1' (if <0.05) or '0' (if >0.05), and producing a table of 5 columns for each of the predictors entered. The table produced in the loop is much smaller than the input table. ?Is there a way to produce a results table using the original column titles of the input table which can be matched to the subset predictors table, where if the variable was not in the subset its row value is 'NA'? I hope that makes sense. Cheers In advance, Matt -- View this message in context: http://r.789695.n4.nabble.com/Adding-rows-to-a-table-with-a-loop-tp3933634p3933634.html Sent from the R help mailing list archive at Nabble.com.
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1 day later
Thanks for the response, and the advice, glmulti looks like it could be quite a good alternative. As for the adding to the results table problem from within the loop, this webpage: <http://ryouready.wordpress.com/2009/01/23/r-combining-vectors-or-data-frames-of-unequal-length-into-one-data-frame/> answered a number of my questions. -- View this message in context: http://r.789695.n4.nabble.com/Adding-rows-to-a-table-with-a-loop-tp3933634p3940293.html Sent from the R help mailing list archive at Nabble.com.