[R] Turn three Columns into a Matrix?

[Ortiz, John]

Subject: Re: [R] Turn three Columns into a Matrix?

On Feb 23, 2010, at 3:18 PM, Ortiz, John wrote:

> Hi all,
>
> If I have a data frame with 3 columns as follows:
>
>> ta
>
> Species       Depth Counts
> spc_a 120     60
> spc_a 140     140
> spc_b 140     5
> spc_b 150     4
> spc_b 180     10
> spc_c 180     10
> spc_c 190     20
>
> How can I turn it into a dataframe or matrix with this structure?:
>
>
>             120       140     140     150     180     180     190
> spc_a      60       0       0       0       0       0       0
> spc_a       0     140      0       0       0       0       0
> spc_b       0       0       5       0       0       0       0
> spc_b       0       0       0       4       0       0       0
> spc_b       0       0       0       0      10       0       0
> spc_c       0       0       0       0       0      10       0
> spc_c       0       0       0       0       0       0       20
>
> I tried with matrify, but this function summarized.
>
> library(labdsv)
> matrify(ta)
>
>      120 140 150 180 190
> spc_a  60 140   0   0   0
> spc_b   0   5   4  10   0
> spc_c   0   0   0  10  20
>
> We are looking by one function similarly to matrify but without
> summary.

Not sure what that last sentence means but here is a a solution to
above request:
 > ta <- read.table(textConnection("
+
+ Species       Depth Counts
+ spc_a 120     60
+ spc_a 140     140
+ spc_b 140     5
+ spc_b 150     4
+ spc_b 180     10
+ spc_c 180     10
+ spc_c 190     20"), header=T)
 > tdiag <- diag(ta$Counts, nrow=nrow(ta), ncol=nrow(ta))
 > rownames(tdiag)<-ta$Species
 > colnames(tdiag)<-ta$Depth
 > tdiag
       120 140 140 150 180 180 190
spc_a  60   0   0   0   0   0   0
spc_a   0 140   0   0   0   0   0
spc_b   0   0   5   0   0   0   0
spc_b   0   0   0   4   0   0   0
spc_b   0   0   0   0  10   0   0
spc_c   0   0   0   0   0  10   0
spc_c   0   0   0   0   0   0  20

Yes this is what I was looking for. Thanks

But this solution doesn't work in my case, because I have 270.000 Rows 

I tried with 10.000 Rows and work good, but 30.000 give me this error:

Error: cannot allocate vector of size 3.4 Gb

And with 270.000  rows this error:

Error in array(0, c(n, p)) : 'dim' specifies too large an array

Somebody Know other solution?

>
> some advice?
>
> Thanks!!
>
> John Ortiz
> Smithsonian Tropical Research Institute
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