[R-sig-Geo] Export subsets of Spatial Points Data Frame to images

[Ariel Fuentesdi]

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(<S4 object of class
"SpatialPointsDataFrame">) :
  no method for coercing this S4 class to a vector
6 as.character.default(<S4 object of class
structure("SpatialPointsDataFrame", package = "sp")>)
5 as.character(<S4 object of class structure("SpatialPointsDataFrame",
package = "sp")>)
4 paste(SB[[1]], ".jpg", sep = "")
3 gsub("%%", "", s)
2 checkIntFormat(filename)
1 jpeg(paste(SB[[1]], ".jpg", sep = ""))**

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