Hi Jeff! Try this: which(mymatrix == 4, arr.ind=TRUE) Hope this help! Sincerely, Erin M. Hodgess, Ph.D. Associate Professor Department of Computer and Mathematical Sciences University of Houston - Downtown One Main Street Houston, TX 77002 e-mail: hodgess at uhddx01.dt.uh.edu Subject: Re: [R] indexing a vector charset="iso-8859-1"
Dear R-List, How can one look up the row/column number for a given value in a matrix
or
data.frame? For example in a matrix that contains only unique values
for
in [,1] how can I find value x in [,1] and report its row number?
match(x,matrix[,1]) -thomas
As a follow up to this question, what's the easiest way to
find the column and row indicies for a specified value in a matrix,
when you don't know which column it's in (as assumed above)?
So if mymatrix <- matrix(c(3, 2, 4, 1), nrow = 2), what's the easiet
way
to see that the value 4 is in position (1, 2) ?
Thanks much,
Jeff Miller
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