On Jun 25, 2009, at 10:24 AM, Rama Ramakrishnan wrote:
Follow-on question: is there a way to do this for higher-dimensional
(i.e.
more than 2 dimensions) arrays?
The apply method I just posted generalizes to higher dimensional arrays.
--
DW
On Thu, Jun 25, 2009 at 10:17 AM, Rama Ramakrishnan
<r...@alum.mit.edu>wrote:
That works!! Very nice way to do it! Thank you, Henrique!
Rama Ramakrishnan
On Thu, Jun 25, 2009 at 10:11 AM, Henrique Dallazuanna <www...@gmail.com
>wrote:
Try this:
y$values <- diag(x[y$ltrs, y$mnths])
On Thu, Jun 25, 2009 at 11:02 AM, Rama Ramakrishnan <r...@alum.mit.edu
>wrote:
Dear R-Users,
I need to lookup values from a 2-d table using the row names and
column
names as indices. I was wondering if there's a way to do this
without an
explicit loop.
Example:
#x is the 2-d table that holds the values
x <- matrix(rnorm(26*12),nrow=26)
rownames(x) <- letters
colnames(x) <- month.name
#y is a data frame that has the "keys" I want to use as indices
into x
y <- data.frame(ltrs=sample(letters,5),mnths=sample(month.name
,5),values=0)
#I want to fill in the "values" column using the "ltrs" and "mnths"
columns
as keys to look up
snip
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