Thank you Petr, Try this
str(by(iris, iris$Species, summary)) and you will see what is actually returned is a list of 3, each element containing a character table, not a numeric table. The rownames of these tables are empty but should contain the names of the summary stats. I have a workaround now. Modified the summary.data.frame method to output numeric values and not the character strings. The rownames I set afterwards in a for loop. Still would like to know how to do this internal to summary.data.frame though. Regards, Alex van der Spek > Hi > >> -----Original Message----- >> From: r-help-boun...@r-project.org [mailto:r-help-bounces@r- >> project.org] On Behalf Of Alex van der Spek >> Sent: Wednesday, October 10, 2012 2:48 PM >> To: r-help@r-project.org >> Subject: [R] Summary using by() returns character arrays in a list >> >> I use by() to generate a summary statistics like so: >> >> Lbys <- by(dat[Nidx], dat$LipTest, summary) >> >> where Nidx is an index vector with names picking out the columns in the >> data frame dat. >> >> This returns a list of character arrays (see below for str() output) >> where the columns are named correctly but the rownames are empty >> strings and the values are strings prepended with the summary >> statistic's name (e.g. >> "Min.", "Median "). > > Without knowledge of your data it is difficult to understand what is > wrong. > > If I use iris data set as input everything goes as expected > data(iris) >> summary(iris) > Sepal.Length Sepal.Width Petal.Length Petal.Width > Min. :4.300 Min. :2.000 Min. :1.000 Min. :0.100 > 1st Qu.:5.100 1st Qu.:2.800 1st Qu.:1.600 1st Qu.:0.300 > Median :5.800 Median :3.000 Median :4.350 Median :1.300 > Mean :5.843 Mean :3.057 Mean :3.758 Mean :1.199 > 3rd Qu.:6.400 3rd Qu.:3.300 3rd Qu.:5.100 3rd Qu.:1.800 > Max. :7.900 Max. :4.400 Max. :6.900 Max. :2.500 > Species > setosa :50 > versicolor:50 > virginica :50 > > > >> by(iris, iris$Species, summary) > iris$Species: setosa > Sepal.Length Sepal.Width Petal.Length Petal.Width > Min. :4.300 Min. :2.300 Min. :1.000 Min. :0.100 > 1st Qu.:4.800 1st Qu.:3.200 1st Qu.:1.400 1st Qu.:0.200 > Median :5.000 Median :3.400 Median :1.500 Median :0.200 > Mean :5.006 Mean :3.428 Mean :1.462 Mean :0.246 > 3rd Qu.:5.200 3rd Qu.:3.675 3rd Qu.:1.575 3rd Qu.:0.300 > Max. :5.800 Max. :4.400 Max. :1.900 Max. :0.600 > Species > setosa :50 > versicolor: 0 > virginica : 0 > > >> >> I am reading the code of summary.data.frame() but can't figure out how >> I can change the action of that function to return list of numeric >> matrices with as rownames the summary statistic's name ("Min.", "Max." >> etc) and as values the numeric values of the calculated summary >> statistic. > > Just what do you not like on such output and how do you want the output > structured? > Maybe you want aggregate, but without simple data it is hard to say. > > aggregate(iris[1:2], list(iris$Species), summary) > > Regards > Petr > >> >> Any help much appreciated! >> Regards, >> Alex van der Spek >> >> >> > str(Lbys) >> List of 2 >> $ : 'table' chr [1:6, 1:19] "Min. :-0.190 " "1st Qu.: 9.297 " >> "Median :10.373 " "Mean :10.100 " ... >> ..- attr(*, "dimnames")=List of 2 >> .. ..$ : chr [1:6] "" "" "" "" ... >> .. ..$ : chr [1:19] "Cell_3_SOS....GVF." "Cell_3_SOSq..ms.ms." >> "Cell_3_Airflow..cfm." "Cell_3_Float..in.." ... >> $ T38: 'table' chr [1:6, 1:19] "Min. :8.648 " "1st Qu.:8.920 " >> "Median :9.018 " "Mean :9.027 " ... >> ..- attr(*, "dimnames")=List of 2 >> .. ..$ : chr [1:6] "" "" "" "" ... >> .. ..$ : chr [1:19] "Cell_3_SOS....GVF." "Cell_3_SOSq..ms.ms." >> "Cell_3_Airflow..cfm." "Cell_3_Float..in.." ... >> - attr(*, "dim")= int 2 >> - attr(*, "dimnames")=List of 1 >> ..$ dat$LipTest: chr [1:2] "" "T38" >> - attr(*, "call")= language by.data.frame(data = dat[Nidx], INDICES = >> dat$LipTest, FUN = summary) >> - attr(*, "class")= chr "by" >> >> ______________________________________________ >> 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. > ______________________________________________ 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.
