On Tue, Jun 17, 2008 at 5:59 AM, Steve Murray <[EMAIL PROTECTED]> wrote:
>
> Dear all,
>
> I have used 'read.table' to create a data frame of 720 columns and 360 rows
> (and assigned this to 'Jan'). The row and column names are numeric:
>
>> columnnames <- sprintf("%.2f", seq(from = -179.75, to = 179.75, length =
>> 720)).
>> rnames <- sprintf("%.2f", seq(from = -89.75, to = 89.75, length = 360))
>> colnames(Jan) <- columnnames
>> rownames(Jan) <- rnames
>
> A sample of the data looks like this:
>
>> head(Jan)
> -179.75 -179.25 -178.75 -178.25 -177.75 -177.25 -176.75 -176.25 -175.75
> -89.75 -56.9 -64.2 56.2 -90.0 56.9 -29.0 -91.0 34.0 -9.1
> -89.25 37.9 19.3 -0.4 -12.3 -11.8 -92.1 9.2 -23.5
> -0.2
> -88.75 47.4 3.1 -47.4 46.4 34.2 6.1 -41.3 44.7
> -10.3
> -88.25 -20.3 34.5 -67.3 -99.9 37.9 -9.3 17.7 -17.2
> 63.4
> -87.75 -46.4 47.4 12.4 -48.3 9.3 -33.8 38.1 10.8
> -34.1
> -87.25 -48.4 10.3 -89.3 -33.0 -1.1 -33.1 81.2 -8.3
> -47.2
>
>
> I'm hoping to get the whole dataset into the form of columns, so that, for
> example, the first row (as shown above) would look like this:
>
> Latitude Longitude Value
> -89.75 -179.75 -56.9
> -89.75 -179.25 -64.2
> -89.75 -178.75 56.2
> -89.75 -178.25 -90.0
> -89.75 -177.75 56.9
> -89.75 -177.25 -29.0
> -89.75 -176.75 -91.0
> -89.75 -176.25 34.0
> -89.75 -175.75 -9.1
>
>
> As you can see, this would require the repeated printing of the the row and
> column names (in this case '-89.75') - so it's not just a case of rearranging
> the data, but creating 'more' data too.
>
> I've tried to achieve this using 'reshape' and 'stack' (their help files and
> after looking through the mailing archives), but I'm obviously doing
> something wrong. For reshape, I'm getting errors relating to the commands I
> enter, and for stack, I can only produce two columns from my data (with the
> additional 3rd column being a row count). In any case, these two columns
> refer to the wrong values (it's producing output in the form of: row count
> number, Longitude, Value).
This is pretty easy with the reshape package:
install.packages("reshape")
library(reshape)
jan_long <- melt(Jan)
You can find out more at http://had.co.nz/reshape
Hadley
--
http://had.co.nz/
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