Re: [R] Matching Up Values
Hmm, I'm having a fair few difficulties using 'merge' now. I managed to get it to work successfully before, but in this case I'm trying to shorten (as oppose to lengthen as before) a file in relation to a 'master' file. These are the commands I've been using, followed by the dimensions of the files in question - as you can see, the row numbers of the merged file don't correlate to that of the 'coordinates' file (which is what I'm aiming to get 'merged' equal to): merge(PopDens.long, coordinates, by=c(Latitude,Longitude), all = TRUE) - merged dim(PopDens.long); dim(coordinates); dim(merged) [1] 67870 3 [1] 67420 2 [1] 69849 3 One thing I tried was swapping the order of the files in the merge command, but this causes 'merged' to have the same number of rows (69849). Something else I tried was to leave out the 'all = TRUE' command, as I'm essentially attempting the shorten the file, but this makes the output file *too* short! (65441 as opposed to the intended 67420). Again, the same applies when the order of the input files are swapped. merge(PopDens.long, coordinates, by=c(Latitude,Longitude)) - merged dim(PopDens.long); dim(coordinates); dim(merged) [1] 67870 3 [1] 67420 2 [1] 65441 3 Am I doing something obviously wrong? I'm pretty certain that 'coordinates' is a subset of 'PopDens.long' - so there should be equal numbers of common values when merged. Is there perhaps a more suitable function I could use, or a way of performing checks to see where I might be going wrong?! Many thanks, Steve _ 100’s of Nikon cameras to be won with Live Search __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] Matching Up Values
I think the approach is ok. I'm having difficulties though...! I've managed to get 'merge' working (using the 'all' function as suggested), but for some strange reason, the output file produces 12 extra rows! So now the shorter file isn't the same length as the 'master' file, it's now longer! The files are fairly sizeable (~6 rows) so it's difficult to pin-point manually where it's lost track. Is there an obvious solution to this? I was wondering if the best thing might be to 'de-merge' the now-longer file, so that the surplus rows are removed. Is there a command therefore which will enable me to compare the now-longer file to the master file, so that any coordinate pairs which are present in the longer file but not in the (now-shorter) master file are removed? Thanks again, Steve _ Play and win great prizes with Live Search and Kung Fu Panda __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] Matching Up Values
On 18/07/2008, at 8:42 AM, Steve Murray wrote:
snip
So what I'm looking to do is, 'pad out' the shorter file, by adding
in the rows with those that are 'missing' from the longer file (ie.
if a particular coordinate isn't present in the shorter file but is
in the 'longer/master' file), and having 'zero' as its Population
Density value (column C).
Aaarrghh!!! Zero is not the same as a missing value.
Surely to gumdrops you should say ``having NA as its Population
Density value''.
Elsewise you are lying about your data.
cheers,
Rolf Turner
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