merge(data1, data2, by.x=c("V1", "V2"), by.y=c("V2", "V1"))
V1 V2 V3
1 47.82 -123.75 11
2 47.82 -123.76 8
library(sqldf)
sqldf("select * from data2 x2, data1 x1 where x2.V1=x1.V2 and
x2.V2=x1.V1")
V1 V2 V3 V1 V2
1 -123.76 47.82 8 -123.76 47.82
2 -123.75 47.82 11 -123.75 47.82
On Mon, Jan 4, 2010 at 7:37 PM, Douglas M. Hultstrand
<dmhultst at metstat.com>wrote:
Hello,
I am trying to match lat/lon from one dataset with the lat/lon from a
second dataset and use that rows data for calculations. I am using
match,
but this is finding the first match and not comparing the pair, how can I
determine if the lat/lon are the same? See example below. Is there a
better way to determine to a matching pair of lat/lon values?
Example Datasets:
V1 V2 V3
1 -123.76 47.82 8
2 -123.75 47.82 11
V1 V2
1 47.82 -123.76
2 47.82 -123.75
3 47.82 -123.74
4 47.82 -123.73
#Subset of current R code :
lat <- data$V1
lon <- data$V2
yrs <- c(1,2,5,10,25,50,100,200,500,1000)
lon2 <- data2$V1
lat2 <- data2$V2
ppt2 <- data2$V3
for(i in 1:length(lat2)) {
loc <- match(lat2[i],lat)
loc2 <- match(lon2[i], lon)
print(loc); print(loc2)
#Need to test to make sure loc equals loc2
freq_ppt <-
c(data[i,4],data[i,6],data[i,8],data[i,10],data[i,12],data[i,14],data[i,16],data[i,18],data[i,20],data[i,22])
print(freq_ppt)
return_value <- approx(freq_ppt,yrs,xout=data2[i,3])
print(return_value)
}
Thanks for your help,
Doug
--
---------------------------------
Douglas M. Hultstrand, MS
Senior Hydrometeorologist
Metstat, Inc. Windsor, Colorado
voice: 970.686.1253
email: dmhultst at metstat.com
web: http://www.metstat.com