R help - Mar 2012 - Remove individual rows from a matrix based upon a list

Dear All,

Thanks in advance for any help.  I have a square matrix of measures of
interactions among individuals and would like to calculate a values from a
function (colSums for example) with a single individual (row) excluded in
each instance.  That individual would be returned to the matrix before the
next is removed and the function recalculated.  I can do this by hand
removing rows based upon ids however I would like specify individuals to be
removed from a list (lots of data).

An example matrix:

MyMatrix
   E985047 E985071 E985088 F952477 F952478 J644805 J644807 J644813  E985047
1 0.09 0 0 0 0 0 0.4  E985071 0.09 1 0 0 0 0 0 0.07  E985088 0 0 1 0 0 0
0.14 0  F952477 0 0 0 1 0.38 0 0 0  F952478 0 0 0 0.38 1 0 0 0  J644805 0 0
0 0 0 1 0.07 0  J644807 0 0 0.14 0 0 0.07 1 0  J644813 0.4 0.07 0 0 0 0 0 1
Example list of individuals to be removed

MyList

E985088






F952477







F952478


If I were to do this by hand it would look like

MyMat1 <- MyMatrix[!rownames(MyMatrix)%in% "E985088",]
colSums(MyMat1)

MyMat2 <-  MyMatrix[!rownames(MyMatrix)%in% " F952477 ",]
colSums(MyMat2)

MyMat3 <-  MyMatrix[!rownames(MyMatrix)%in% " F952478 ",]
colSums(MyMat3)

How might I replace the individual ids (in quotes) with a list and remove
rows corresponding to that list from the matrix for the calculation and
returning the row to the list after each calculation before the next.

I hope I've been clear!!

	[[alternative HTML version deleted]]

Hello,
>
> Thanks in advance for any help.  I have a square matrix of measures of
> interactions among individuals and would like to calculate a values from a
> function (colSums for example) with a single individual (row) excluded in
> each instance.  That individual would be returned to the matrix before the
> next is removed and the function recalculated. 
> 
Try


MyMatrix <- structure(list(V2 = c(1, 0.09, 0, 0, 0, 0, 0, 0.4), V3 = c(0.09, 
1, 0, 0, 0, 0, 0, 0.07), V4 = c(0, 0, 1, 0, 0, 0, 0.14, 0), V5 = c(0, 
0, 0, 1, 0.38, 0, 0, 0), V6 = c(0, 0, 0, 0.38, 1, 0, 0, 0), V7 = c(0, 
0, 0, 0, 0, 1, 0.07, 0), V8 = c(0, 0, 0.14, 0, 0, 0.07, 1, 0), 
    V9 = c(0.4, 0.07, 0, 0, 0, 0, 0, 1)), .Names = c("V2",
"V3",
"V4", "V5", "V6", "V7", "V8",
"V9"), class = "data.frame", row.names
c("E985047",
"E985071", "E985088", "F952477",
"F952478", "J644805", "J644807",
"J644813"))

MyList <- c("E985088", "F952477", "F952478")


inx <- which(rownames(MyMatrix) %in% MyList)

result <- lapply(inx, function(i) colSums(MyMatrix[-i, ]))

# Not needed, but makes what is what more clear 
names(result) <- paste("Without", MyList, sep=".")
result
>
> I hope I've been clear!! 
>
I believe you were, but your data is a mess.
The structures above were produced with function 'dput', it makes it
much,
much easier to create the objects.
See

?dput

and use it!

Hope this helps,

Rui Barradas


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