Displaying 5 results from an estimated 5 matches for "redcell".
2018 May 20
1
How to average values from grid cells with coordinates
...b="Longitude",ylab="Latitude")
abline(h=27.5)
abline(h=lat+0.5)
abline(v=97.5)
abline(v=lon+0.5)
text(blackcells$lon,blackcells$lat,pop)
# the red cells will be centered on the corners of 4 black cells
lat2<-rep(seq(28.5,34.5,by=2),4)
lon2<-rep(seq(99.5,105.5,by=2),each=4)
redcells<-data.frame(lat=lat2,lon=lon2,value=NA)
display the red cells
rect(lon2-1,lat2-1,lon2+1,lat2+1,border="red",lwd=2)
nblackcells<-dim(blackcells)[1]
nredcells<-dim(redcells)[1]
for(redcell in 1:nredcells) {
close4<-rep(NA,4)
closen<-1
for(blackcell in 1:nblackcells) {
i...
2018 May 22
0
How to average values from grid cells with coordinates
Hi Jim,
Thanks. It works. I now have more complex problems. If at each blackcell,
there are two variables such as pop and mood. For each variable, there are
daily records in one year, so 365 records for pop and 365 records for mood.
The averaged values for the redcells should be daily records too. What kind
of format do you recommend for this problem? Right now, I just get the
latitudes and longitudes into a dataframe. Thanks.
On Sun, May 20, 2018 at 3:52 AM, Jim Lemon <drjimlemon at gmail.com> wrote:
> Hi lily,
> It's not too hard to do it usi...
2018 May 16
0
How to average values from grid cells with coordinates
...uot; cells by finding the lat/lon values that
are closest to the "red" lat/lon values. Here's a basic example:
lat<-rep(28:38,11)
lon<-rep(98:108,each=11)
pop<-sample(80:200,121)
blackcells<-list()
for(i in 1:121) blackcells[[i]]<-list(lat=lat[i],lon=lon[i],pop=pop[i])
redcell<-list(lat=33.5,lon=100.5,pop=NA)
close4<-rep(NA,4)
closen<-1
for(i in 1:121) {
if(abs(blackcells[[i]]$lat-redcell$lat) < 1 &&
abs(blackcells[[i]]$lon-redcell$lon) < 1) {
close4[closen]<-i
closen<-closen+1
}
}
cat(close4,"\n")
redcell$pop<-(blackcell...
2018 May 16
5
How to average values from grid cells with coordinates
Hi R users,
I have a question about data processing. I have such a dataset, while each
black grid cell has a few attributes and the corresponding attribute
values. The latitude and longitude of the center of each grid cell are
given also.
Then I want to average the attribute values from four adjacent grid cells
to get the average value for the center of each red grid cell. Thus, there
are the
2018 May 19
0
How to average values from grid cells with coordinates
...uot;red"
cell.
Jim
On Sat, May 19, 2018 at 4:07 AM, lily li <chocold12 at gmail.com> wrote:
> Hi Jim,
>
> Thanks. Yes, the two assumptions are correct, and they reflect the datasets.
> I have an uncertainty about the code below. Why do you use
> abs(blackcells[[i]]$lat - redcell$lat) <1 rather than a different number
> than 1? Second, why to construct blackcells as a list, rather than a
> dataframe. Because in a dataframe, each row can represent one grid cell,
> while the three columns can represent the lati, lon, and pop. Thanks again
> for your help.
>...