How can I keep polygons's information after shapefile? Let me try to explain:
I have a shapefile with this data:
> head(mapa@data)
ID CD_GEOCODI TIPO CD_GEOCODB NM_BAIRRO CD_GEOCODS NM_SUBDIST CD_GEOCODD NM_DISTRIT CD_GEOCODM NM_MUNICIP NM_MICRO NM_MESO
12228 33679 431490205000133 URBANO 431490205003 Cidade Baixa 43149020500 <NA> 431490205 PORTO ALEGRE 4314902 PORTO ALEGRE PORTO ALEGRE METROPOLITANA DE PORTO ALEGRE
12229 33680 431490205000134 URBANO 431490205003 Cidade Baixa 43149020500 <NA> 431490205 PORTO ALEGRE 4314902 PORTO ALEGRE PORTO ALEGRE METROPOLITANA DE PORTO ALEGRE
12230 33681 431490205000135 URBANO 431490205003 Cidade Baixa 43149020500 <NA> 431490205 PORTO ALEGRE 4314902 PORTO ALEGRE PORTO ALEGRE METROPOLITANA DE PORTO ALEGRE
12231 33682 431490205000136 URBANO 431490205003 Cidade Baixa 43149020500 <NA> 431490205 PORTO ALEGRE 4314902 PORTO ALEGRE PORTO ALEGRE METROPOLITANA DE PORTO ALEGRE
12232 33683 431490205000137 URBANO 431490205003 Cidade Baixa 43149020500 <NA> 431490205 PORTO ALEGRE 4314902 PORTO ALEGRE PORTO ALEGRE METROPOLITANA DE PORTO ALEGRE
12233 33684 431490205000138 URBANO 431490205003 Cidade Baixa 43149020500 <NA> 431490205 PORTO ALEGRE 4314902 PORTO ALEGRE PORTO ALEGRE METROPOLITANA DE PORTO ALEGRE
and this data:
> head(data)
CD_GEOCODI Population
1 431490205000133 1272
2 431490205000134 822
3 431490205000135 1085
4 431490205000136 1454
5 431490205000137 964
6 431490205000138 834
I could just merge data
and mapa@data
and plot it with plot()
, but I want use ggplot2. But fortify()
's output donsn't have any of originals variables. For example:
> head(fortify(mapa))
Regions defined for each Polygons
long lat order hole piece group id
1 -51.22254 -30.03526 1 FALSE 1 12228.1 12228
2 -51.22332 -30.03648 2 FALSE 1 12228.1 12228
3 -51.22365 -30.03702 3 FALSE 1 12228.1 12228
4 -51.22482 -30.03610 4 FALSE 1 12228.1 12228
5 -51.22488 -30.03606 5 FALSE 1 12228.1 12228
6 -51.22476 -30.03591 6 FALSE 1 12228.1 12228
Both (fortify and mapa@data) have an id variable, but aren't the same values. So, again, my question is: How can I pass mapa@data
's information to fortify()
's output (or another function that allows use ggplot2)
Shapefile Metadata & Attributes When we import the HarClip_UTMZ18 shapefile layer into R (as our aoi_boundary_HARV object), the st_read() function automatically stores information about the data.
Description. The fortify function converts an S3 object generated by evalmod to a data frame for ggplot2.
Shapefiles are a common way to store geospatial data. This post explains how to read it with R and the rgdal package, and how to plot it in base R or with ggplot2 . Background map section About Maps.
Since you did not provide your shapefile or data, it's impossible to test, but something like this should work:
# not tested...
library(plyr) # for join(...)
library(rgdal) # for readOGR(...)
library(ggplot2) # for fortify(...)
mapa <- readOGR(dsn=".",layer="shapefile name w/o .shp extension")
map@data$id <- rownames(mapa@data)
mapa@data <- join(mapa@data, data, by="CD_GEOCODI")
mapa.df <- fortify(mapa)
mapa.df <- join(mapa.df,mapa@data, by="id")
ggplot(mapa.df, aes(x=long, y=lat, group=group))+
geom_polygon(aes(fill=Population))+
coord_fixed()
Maybe this is a slightly simpler solution
library(dplyr)
library(ggplot2)
# fortify the shape file
map.df <- fortify(shape, region ="CD_GEOCODI")
# merge data
map.df <- left_join(map.df, data, by=c('id'='CD_GEOCODI'))
I came across the same problem and was able to achieve the desired results using slightly different approach.
I have used the following code to read the shapes:
shps <- maptools::readShapePoly(fn = file.path("file",
"path",
"no extension"),
# Column with unique IDs
IDvar = "geoID")
and subsequently fortified the objet using the code:
shpsFort <- ggplot2::fortify(model = shps)
This created a data.frame object with the id
value corresponding to the column passed in IDvar = "geoID"
. Adding any other data could be simply addressed via ordinary merge
command.
Assumption that data$CD_GEOCODI and shape@data are both unique for each row. Below is a better and simpler answer:
library(dplyr)
library(ggplot2)
# fortify the shape file
map.df <- fortify(shape, region ="CD_GEOCODI")
# change data$CD_GEOCODI to character, as shp.df$CD_GEOCODI is of character class.
data <- data %>% mutate(data, CD_GEOCODI = as.character(CD_GEOCODI))
# merge data
map.df <- left_join(map.df, data, by=c('id'='CD_GEOCODI'))
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