contourplot by year
On Jul 10, 2010, at 5:58 PM, Sally_roman wrote:
Hi - I have a dataframe with 4 variables - long, lat, temp and year. I would like to plot temperature by lat and long in contour plots by year. There are 391 data points. When I try contourplot(temp~long*lat|year,data=hake,cuts=10,labels = TRUE,contour = TRUE,pretty = TRUE,region=TRUE) I get plots with dots around by data, but not contour lines or filled in regions. I have also used the intrep function with image and contour which works fine, but I have to subset by data by year first before I make the graphs. I tried to use grid<-expand.grid(x=x,y=y) after reading some other questions on Nabble about using contourplot with irregular data points. When I run the contourplot contourplot(z~x*y|hake$year,data=grid,cuts=10,labels = TRUE,contour = TRUE,pretty = TRUE,region=TRUE) I get an error message in the plot: Error using packet 4 no proper 'z' matrix specified. I tried to use expand.grid(x=x,y=y,z=z),
Expand.grid(x,y) might be useful for setting up a structure but you then need to add a z variable that is appropriate for each row of the x-by-y grid. You do not want an x-by-y-by-z grid. Look mor closely at the example on the help apge for contourplot. The "fit" columns is not given as an argument to expand.grid.
but get an error message that R cannot allocate vector of size 3.1 Gb.
David Winsemius, MD West Hartford, CT