Hi, I am having a problem figuring out how to extract a subset of rows. I have a list with 68 similar data.frames. Each data.frame is 500 rows by 5 columns. I want to take one row from each data.frame based upon the data in a particular column (i.e. it matches a symbol). For example:
> str(database) List of 68 $ X2011.01.11:'data.frame': 500 obs. of 5 variables: ..$ Symbol : chr [1:500] "MMM" "ACE" "AES" "AFL" ... ..$ Price : num [1:500] 87.7 60.7 13.1 55.7 15.6 ... ..$ Shares.Out: num [1:500] 7.15e+08 3.39e+08 7.88e+08 4.71e+08 1.10e+08 ... ..$ Float : num [1:500] 7.13e+08 3.38e+08 6.61e+08 4.60e+08 1.09e+08 ... ..$ Market.Cap: num [1:500] 6.27e+10 2.06e+10 1.04e+10 2.62e+10 1.72e+09 ... $ X2011.01.12:'data.frame': 500 obs. of 5 variables: ..$ Symbol : chr [1:500] "MMM" "ACE" "AES" "AFL" ... ..$ Price : num [1:500] 88.7 60.9 12.9 57.1 15.2 ... ..$ Shares.Out: num [1:500] 7.15e+08 3.39e+08 7.88e+08 4.71e+08 1.10e+08 ... ..$ Float : num [1:500] 7.13e+08 3.38e+08 6.61e+08 4.60e+08 1.09e+08 ... ..$ Market.Cap: num [1:500] 6.34e+10 2.06e+10 1.02e+10 2.69e+10 1.68e+09 ... . . . > lapply(database, function(x) which(x == "IBM")) $X2011.01.11 [1] 234 $X2011.01.12 [1] 234 . . . > lapply(database, function(x) x[which(x == "IBM"), ]) $X2011.01.11 Symbol Price Shares.Out Float Market.Cap 234 IBM 147.28 1.24e+09 1.24e+09 1.8297e+11 $X2011.01.12 Symbol Price Shares.Out Float Market.Cap 234 IBM 149.1 1.24e+09 1.24e+09 1.8524e+11 . . . What I would like to do is create a new data.frame with 68 rows by 5 columns of data, perhaps using the old data.frame names as the new row.names. I can get to the subset of data that I want, I just can't get it from list form into one new data.frame. Any suggestions? Thank you. James ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.