Export to images subsets of Spatial Points Data Frame

Question

I have a csv file, which I converted it to Spatial Points Data Frame. And I want to split the spatial data and export each map to a jpg file.

I did the following:

SB <- read.csv("SB_040914.csv", header=TRUE, sep = ";")
SB <- SB %>% group_by(Fecha, CodPar, x, y) %>% summarise(mean(Sube),mean(Evade), mean(Baja))
SB <- data.frame(SB)
SB <- SB[complete.cases(SB),]

coordinates(SB) <- ~ x + y 
proj4string(obj = SB) <- CRS("+init=epsg:32719")

SB <- split(SB, f = SB$Fecha)  

The Split function, shows me the next warnings:

Warning messages: 1: In min(x) : no non-missing arguments to min; returning Inf 2: In max(x) : no non-missing arguments to max; returning -Inf 3: In min(x) : no non-missing arguments to min; returning Inf 4: In max(x) : no non-missing arguments to max; returning -Inf

And for trying to export I did this:

for (i in SB) {  
  jpeg(paste(SB[[1]],".jpg",sep=""))
  bubble(SB[[i]], "mean.Evade.", col=c("#00ff0088", "#00ff0088"), 
         main = "Evasión" )
  dev.off()
}

Which shows me the next error: Error in as.character.default() : no method for coercing this S4 class to a vector 6 as.character.default() 5 as.character() 4 paste(SB[[1]], ".jpg", sep = "") 3 gsub("%%", "", s) 2 checkIntFormat(filename) 1 jpeg(paste(SB[[1]], ".jpg", sep = ""))

As you can see, this is made in R.

The link to the data: https://www.sendspace.com/file/nd6j8h

Answer 1

The split command requires a data frame or vector and you are giving it a SpatialPointsDataFrame. All you have to do is to do the split first and then create your SpatialPointsDataFrame. Below is the complete code for this.

library(sp)
library(dplyr)
SB <- read.csv("SB_040914.csv", header=TRUE, sep = ",")

SB <- SB %>% group_by(Fecha, CodPar, x, y) %>% summarise(mean(Sube),mean(Evade), mean(Baja))
SB <- data.frame(SB)
SB <- SB[complete.cases(SB),]

# split here!
SB <- split(SB, f = SB$Fecha)

# then produce the maps
lapply(SB, function(x) {
  coordinates(x) <- ~x + y
  proj4string(x) <- CRS("+init=epsg:32719")
  jpeg(print((paste0(gsub("/", "_", x$Fecha[1]),".jpg"))))
  print(bubble(x, "mean.Evade.", col=c("#00ff0088", "#00ff0088"), main = "Evasión" ))
  dev.off()
})