Hello all, I need to extract rows and columns from a data frame and put
them in a matrix. In some cases, there are no rows in the data frame
meeting the selection criteria. For those rows I want to put a row of
0's in the matrix. Here's my clumsy code:
tab1.m1 <- matrix(0, nrow=2, ncol=4)
tab1.m1[1,] <- ifelse(length(as.matrix(tab1[tab1$comp==the.comp &
tab1$schlid==the.schl & tab1$ext.obs==0, 4:7])) > 0,
as.matrix(subset(tab1, tab1$comp==the.comp &
tab1$schlid==the.schl & tab1$ext.obs==0)[4:7]),
0)
The row of data I want to put in the matrix is:
tab1[tab1$comp==the.comp & tab1$schlid==the.schl & tab1$ext.obs==0,]
schlid ext.obs comp 1 2 3 4 NA
41 22091 0 1 0.04166667 0.04166667 0.7083333 0.2083333 0
If I do this:
tab1.m1[1,] <- as.matrix(subset(tab1, tab1$comp==the.comp &
tab1$schlid==the.schl & tab1$ext.obs==0)[4:7])
I get the correct values in the matrix:> tab1.m1[1,] <- as.matrix(subset(tab1, tab1$comp==the.comp &
tab1$schlid==the.schl & tab1$ext.obs==0)[4:7])
> tab1.m1
[,1] [,2] [,3] [,4]
[1,] 0.04166667 0.04166667 0.7083333 0.2083333
[2,] 0.00000000 0.00000000 0.0000000 0.0000000
but when I use the ifelse() as above, I get this:
[,1] [,2] [,3] [,4]
[1,] 0.04166667 0.04166667 0.04166667 0.04166667
[2,] 0.00000000 0.00000000 0.00000000 0.00000000
Can anyone explain this to me?
Also, is there an easier, less clumsy way to test for the existence of a
row in a data frame?
Thanks in advance.
--
Stuart Luppescu -=- slu .at. ccsr.uchicago.edu
University of Chicago -=- CCSR
???????? -=- Kernel 2.6.39-gentoo-r3
You can't expect statistical procedures to rescue
you from poor data. -- Berton Gunter (on
dealing with missing values in a cluster analysis)
R-help (April 2005)
On Aug 16, 2011, at 1:10 PM, Stuart Luppescu wrote:> Hello all, I need to extract rows and columns from a data frame and > put > them in a matrix. In some cases, there are no rows in the data frame > meeting the selection criteria. For those rows I want to put a row of > 0's in the matrix. Here's my clumsy code: > > tab1.m1 <- matrix(0, nrow=2, ncol=4) > > tab1.m1[1,] <- ifelse(length(as.matrix(tab1[tab1$comp==the.comp & > tab1$schlid==the.schl & tab1$ext.obs==0, 4:7])) > 0,> as.matrix(subset(tab1, tab1$comp==the.comp & tab1$schlid==the.schl & > tab1$ext.obs==0)[4:7]),Missing comma about here -----------------------------------------------------------------^> 0) > The row of data I want to put in the matrix is: > > tab1[tab1$comp==the.comp & tab1$schlid==the.schl & tab1$ext.obs==0,] > schlid ext.obs comp 1 2 3 4 NA > 41 22091 0 1 0.04166667 0.04166667 0.7083333 0.2083333 0 > > If I do this: > > tab1.m1[1,] <- as.matrix(subset(tab1, tab1$comp==the.comp & > tab1$schlid==the.schl & tab1$ext.obs==0)[4:7]) > > I get the correct values in the matrix: >> tab1.m1[1,] <- as.matrix(subset(tab1, tab1$comp==the.comp & >> tab1$schlid==the.schl & tab1$ext.obs==0)[4:7]) >> tab1.m1 > [,1] [,2] [,3] [,4] > [1,] 0.04166667 0.04166667 0.7083333 0.2083333 > [2,] 0.00000000 0.00000000 0.0000000 0.0000000 > > but when I use the ifelse() as above, I get this: > [,1] [,2] [,3] [,4] > [1,] 0.04166667 0.04166667 0.04166667 0.04166667 > [2,] 0.00000000 0.00000000 0.00000000 0.00000000 > > Can anyone explain this to me? > Also, is there an easier, less clumsy way to test for the existence > of a > row in a data frame? > > Thanks in advance. > -- > Stuart Luppescu -=- slu .at. ccsr.uchicago.edu > University of Chicago -=- CCSR > ???????? -=- Kernel 2.6.39-gentoo-r3 > You can't expect statistical procedures to rescue > you from poor data. -- Berton Gunter (on > dealing with missing values in a cluster analysis) > R-help (April 2005) > > > > > > ______________________________________________ > R-help at 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.David Winsemius, MD West Hartford, CT
On Tue, 2011-08-16 at 12:10 -0500, Stuart Luppescu wrote:> but when I use the ifelse() as above, I get this: > [,1] [,2] [,3] [,4] > [1,] 0.04166667 0.04166667 0.04166667 0.04166667 > [2,] 0.00000000 0.00000000 0.00000000 0.00000000Oh, I see. ifelse() returns a value of the same length as the test argument. -- Stuart Luppescu -=- slu .at. ccsr.uchicago.edu University of Chicago -=- CCSR ???????? -=- Kernel 2.6.39-gentoo-r3 This reminds me of a famous FORTRAN code snippet: 10 STOP STOP STOP ! IN CASE STILL SKIDDING GOTO 10 -- Carl Witthoft (in response to the question how to completely stop R scripts after stop()) R-help (January 2011)