"Argument of length zero" in R -

i have data , dont know how make plot it, wirte script change form

and here result of dput(head(e1)):

structure(list(lon = c(-26.583, -26.25, -26.417, -67.25, -67.25,  -67.417), lat = c(-59.083, -58.417, -58.417, -55.917, -55.75,  -55.75), pre1 = c(105.4, 106.3, 106.6, 73.1, 68.7, 70.2)), .names = c("lon",  "lat", "pre1"), row.names = c(na, 6l), class = "data.frame") 

the first column longitude , second 1 latitude, third 1 precipitation value of point. want make map data, dont know how deal format, want change 3 matrix: 1 longitude,one latitude, 1 precipitation, , can use function image.plot(lon,lat,pre1) make map of precipitation.

this script:

rerange<-function(e1) { latq<-sort(e1$lat,decreasing = t) latq<-as.matrix(latq) latq1<-unique.matrix(latq) lonq<-sort(e1$lon) lonq<-as.matrix(lonq) lonq1<-unique.matrix(lonq) lenlon<-length(lonq1) lenlat<-length(latq1) finalq<-matrix(0,lenlon,lenlat) (i in 1:lenlat) {   (j in 1:lenlon) {       finalq[i,j]<-e1$pre1[e1$lon == lonq1[j] & e1$lat == latq1[i] ]     }   } return(finalq) } 

but return error this:

error in finalq[i, j] <- e1$pre1[e1$lon == lonq1[j] & e1$lat == latq1[i]] :  replacement has length 0 

i have try other ways, unable figure out error.how can fix it? assistance appreciated.

ok, checking out data, think more or less after:

# create dataframe df <- structure(list(lon = c(-26.583, -26.25, -26.417, -67.25, -67.25,                     -67.417), lat = c(-59.083, -58.417, -58.417, -55.917, -55.75,                                       -55.75), pre1 = c(105.4, 106.3, 106.6, 73.1, 68.7, 70.2)), .names = c("lon",                                                                                                             "lat", "pre1"), row.names = c(na, 6l), class = "data.frame")  # change long wide format test <- reshape(df, timevar = "lat", idvar = "lon", direction = "wide") # turn missing values zeros test[is.na(test)] <- 0 # use lon rownames rownames(test) <- test[, 1] # drop first column test <- test[,c(2:5)] # load stringr library library(stringr) # drop text column names colnames(test) <- str_replace(colnames(test), "pre1.", "") # put rownames , colnames increasing order test <- test[order(rownames(test), decreasing = true), order(colnames(test), decreasing = true)] test # load plotting library library(fields) # make plot image.plot(as.numeric(rownames(test)), as.numeric(colnames(test)),  as.matrix(test)) 

is need?