R help - Jul 2011 - for loop help

I am having a hard time putting the below into a loop, where it pulls out ppt
from all he stations I have versus having to go through and hard code the data
to the specific stations. I tried
stnID <- stnid[which(duplicated(stnid)==FALSE)]
for(i in 1:length(stnID))
{
ppt[i] <- ppt[which(stnid==[i])]
}

but it doesn't like to use the which function inside a for loop? Any
idea's here is a sample of my code... thanks-Cassie

### label data ###
stnid <- dat1[,1] #list of stations
lat <- dat1[,2] #latitude of station
lon <- dat1[,3] #longitude of station
year <- dat1[,4] # data year
month <- dat1[,5] #data month
ppt <- dat2 #precipiation data


#### station's missing zero years ###
ppt2  <- matrix(ppt[,which(stnid == '140365')],ncol=1)
year2 <- year[which(stnid == '140365')]
year2 <- year2[which(duplicated(year2) == FALSE)]
month2 <- month[which(stnid == '140365')]

ppt3  <- matrix(ppt[,which(stnid == '140405')],ncol=1)
year3 <- year[which(stnid == '140405')]
year3 <- year3[which(duplicated(year3) == FALSE)]
month3 <- month[which(stnid == '140405')]

Hi Cassie,

I'm not sure exactly what you are trying to get: i assume that each
station will have a different ppt value for each year-month
combination, but it looks like you're trying to get one ppt value for
each station.

Steve


On Thu, Jul 28, 2011 at 1:30 AM, Wilson, Cassandra J <cwils11 at ku.edu>
wrote:
> I am having a hard time putting the below into a loop, where it pulls out
ppt from all he stations I have versus having to go through and hard code the
data to the specific stations. I tried
> stnID <- stnid[which(duplicated(stnid)==FALSE)]
> for(i in 1:length(stnID))
> {
> ppt[i] <- ppt[which(stnid==[i])]
> }
>
> but it doesn't like to use the which function inside a for loop? Any
idea's here is a sample of my code... thanks-Cassie
>
> ### label data ###
> stnid <- dat1[,1] #list of stations
> lat <- dat1[,2] #latitude of station
> lon <- dat1[,3] #longitude of station
> year <- dat1[,4] # data year
> month <- dat1[,5] #data month
> ppt <- dat2 #precipiation data
>
>
> #### station's missing zero years ###
> ppt2 ?<- matrix(ppt[,which(stnid == '140365')],ncol=1)
> year2 <- year[which(stnid == '140365')]
> year2 <- year2[which(duplicated(year2) == FALSE)]
> month2 <- month[which(stnid == '140365')]
>
> ppt3 ?<- matrix(ppt[,which(stnid == '140405')],ncol=1)
> year3 <- year[which(stnid == '140405')]
> year3 <- year3[which(duplicated(year3) == FALSE)]
> month3 <- month[which(stnid == '140405')]
>
> ______________________________________________
> R-help at 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.
>

I'm not sure what you're doing... but here are some tips about the parts
I
can understand.

1) you don't need to use "which" as much.  This works fine:
     stnID <- stnid[!duplicated(stnid)]

2) "which" works within a for loop

3) Do you realize that "stnID" is shorter after you removed
duplicates?  I
think it might be the wrong length for your loop function.

4) You can loop over things directly rather than their index.  E.g.:
     for(stn in stnID) print(stn)


On Wed, Jul 27, 2011 at 10:30 AM, Wilson, Cassandra J
<cwils11@ku.edu>wrote:
> I am having a hard time putting the below into a loop, where it pulls out
> ppt from all he stations I have versus having to go through and hard code
> the data to the specific stations. I tried
> stnID <- stnid[which(duplicated(stnid)==FALSE)]
> for(i in 1:length(stnID))
> {
> ppt[i] <- ppt[which(stnid==[i])]
> }
>
> but it doesn't like to use the which function inside a for loop? Any
idea's
> here is a sample of my code... thanks-Cassie
>
> ### label data ###
> stnid <- dat1[,1] #list of stations
> lat <- dat1[,2] #latitude of station
> lon <- dat1[,3] #longitude of station
> year <- dat1[,4] # data year
> month <- dat1[,5] #data month
> ppt <- dat2 #precipiation data
>
>
> #### station's missing zero years ###
> ppt2  <- matrix(ppt[,which(stnid == '140365')],ncol=1)
> year2 <- year[which(stnid == '140365')]
> year2 <- year2[which(duplicated(year2) == FALSE)]
> month2 <- month[which(stnid == '140365')]
>
> ppt3  <- matrix(ppt[,which(stnid == '140405')],ncol=1)
> year3 <- year[which(stnid == '140405')]
> year3 <- year3[which(duplicated(year3) == FALSE)]
> month3 <- month[which(stnid == '140405')]
>
> ______________________________________________
> 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.
>
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