Re: [R] get cells by the combination of their column and row names
On Apr 20, 2011, at 3:52 PM, yoav baranan wrote:
Hi,
I have a (correlation) matrix and I want to select a subset of its
cells depending on the combination of their column and row names.
This illustrates my problem: mtrx <- matrix(c(1,2,3,4,5,6,7,8,9),
nrow=3, ncol=3, dimnames = list(c('c132','c432', 'c233'),
c('r132','r233', 'r432')))> mtrx r132 r233 r432c13214
7c432258c233369
At this point I want to compute the mean of the cells in which the
column and the row names share the same suffix (i.e., the cells
mtrx[1,1], mtrx[2,3], mtrx[3,2]). By suffix I mean the last three
digits of the row/col name.
I need a generic code (and not vec<-c(mtrx[1,1], mtrx[2,3],
mtrx[3,2])) because I don't know in advance how many rows and
columns I will have (currently 118).
> mtrx[ sub("r|c", "", rep(rownames(mtrx),times=3) ) ==
sub("r|c", "", rep(colnames(mtrx), each=3))]
[1] 1 6 8
> mean( mtrx[ sub("r|c", "", rep(rownames(mtrx),times=3) ) ==
sub("r|c", "", rep(colnames(mtrx), each=3))] )
[1] 5
Obviously you need to substitute NROW() and NCOL() vlues for the rep
arguments but that should be simple.
Thanks, Yoav
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Re: [R] get cells by the combination of their column and row names
Yoav -
Here's one possibility:
wh = outer(rownames(mtrx),colnames(mtrx),
+ function(x,y)substr(x,nchar(x)-2,nchar(x)) ==
substr(y,nchar(y)-2,nchar(y)))
mtrx[wh]
[1] 1 6 8
If you knew that all of the row and column names were 4 characters long, it
would simplify to
mtrx[outer(rownames(mtrx),colnames(mtrx),function(x,y)substr(x,2,4) ==
substr(y,2,4))]
Hope this helps.
- Phil Spector
Statistical Computing Facility
Department of Statistics
UC Berkeley
spec...@stat.berkeley.edu
On Wed, 20 Apr 2011, yoav baranan wrote:
Hi,
I have a (correlation) matrix and I want to select a subset of its cells
depending on the combination of their column and row names.
This illustrates my problem: mtrx <- matrix(c(1,2,3,4,5,6,7,8,9), nrow=3, ncol=3,
dimnames = list(c('c132','c432', 'c233'), c('r132','r233', 'r432')))> mtrx
r132 r233 r432c132147c432258c233369
At this point I want to compute the mean of the cells in which the column and
the row names share the same suffix (i.e., the cells mtrx[1,1], mtrx[2,3],
mtrx[3,2]). By suffix I mean the last three digits of the row/col name.
I need a generic code (and not vec<-c(mtrx[1,1], mtrx[2,3], mtrx[3,2])) because
I don't know in advance how many rows and columns I will have (currently 118).
Thanks, Yoav
[[alternative HTML version deleted]]
__
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
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
[R] get cells by the combination of their column and row names
Hi,
I have a (correlation) matrix and I want to select a subset of its cells
depending on the combination of their column and row names.
This illustrates my problem: mtrx <- matrix(c(1,2,3,4,5,6,7,8,9), nrow=3,
ncol=3, dimnames = list(c('c132','c432', 'c233'), c('r132','r233', 'r432')))>
mtrx r132 r233 r432c132147c432258c233369
At this point I want to compute the mean of the cells in which the column and
the row names share the same suffix (i.e., the cells mtrx[1,1], mtrx[2,3],
mtrx[3,2]). By suffix I mean the last three digits of the row/col name.
I need a generic code (and not vec<-c(mtrx[1,1], mtrx[2,3], mtrx[3,2])) because
I don't know in advance how many rows and columns I will have (currently 118).
Thanks, Yoav
[[alternative HTML version deleted]]
__
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.
