[R-sig-Geo] Labelling a fortified GADM map plotted with ggplot and geom_map

[Kenneth Dyson]

Pardon, mistakenly hit reply instead of reply-all.

Thanks for taking interest

I can’t figure out how to merge my collected data into the shapefile without first changing it to a df.
Is there something simple I am missing?
I will read up on tmap in greater detail asap, but if there is a simple solution to getting the data into the shape file and plotting with data labels please let me know.

Cheers

On Mar 19, 2018, 12:40 PM -0400, Roger Bivand <Roger.Bivand at nhh.no>, wrote:
> On Mon, 19 Mar 2018, Kenneth Dyson wrote:
>
> > Reffered here from the R-Help mailing list:
> >
> > I am having trouble getting data labels to display over the provinces in
> > a GADM map of Canada. Specifically, I need the variable "Number" from
> > the data set "by_province", grouped by "region", to appear on the
> > corresponding regions of the map.
>
> You are making life unnecessarily difficult. Use the tmap package instead,
> see for example:
>
> https://www.johnmackintosh.com/2017-09-01-easy-maps-with-tmap/
>
> using the sf representation and forgetting ggplot2 (the development
> version supports geom_sf, but hasn't been released).
>
> Roger
>
> >
> > The data set "by_province" looks like this:
> >
> > long      lat          order  hole piece                   region                group     Number
> > -110.37074 60.00006       1 FALSE     1            Alberta            Alberta.1    132
> > -110.36250 60.00006       2 FALSE     1            Alberta            Alberta.1    132
> > -110.35103 60.00006       3 FALSE     1            Alberta            Alberta.1    132
> >
> > and the data set "tract" is the map data without the "Number" variable.
> >
> > I looked into working this out from by researching the geom_map function here: http://ggplot2.tidyverse.org/reference/geom_map.html
> >
> > my code looks like this:
> > # get the raw map data
> > can_map <- getData('GADM', country = "CAN", level = 1) # download map level with provinces
> > tract <- fortify(can_map, region = "NAME_1") # transforms data from shapefiles into a dataframe that ggplot can understand, from http://www.kevjohnson.org/making-maps-in-r/
> >
> > # create subsets of the kcj data if needed, for example by year
> > kids_data_2017 <- subset(kids_data, year == 2017) # data for the year 2017
> > kids_data_2018 <- subset(kids_data, year == 2018) # data for the year 2018
> >
> > # extract the needed data
> > kids_province_data <- data.table::data.table(kids_data_2017$Province_Territory__c, kids_data_2017$Number_of_kids__c)
> > names(kids_province_data)[1] <- "Province"
> > names(kids_province_data)[2] <- "Number"
> >
> > # sum the data by province
> > kids_province_sums <- aggregate(.~Province, data = kids_province_data, sum)
> >
> > # join the data to the map
> > names(tract)[6] <- "region"
> > names(kids_province_sums)[1] <- "region"
> > by_province <- left_join(tract, kids_province_sums)
> >
> > # create the data map
> > kids_map <- ggplot(by_province, aes(map_id = region)) +              #plots the map in by_province separating by region
> >            geom_map(aes(fill = Number),                             #generates aestheticsa for the plot
> >                     map = tract,                                        #takes the data from tract
> >                     color = "#ffffff",                                  #makes the color of the borders between regions white
> >                     size = 0.15) +                                      #sets the thickness of the boarder lines
> >            coord_map("polyconic") +                                 #sets the coordinates to polyconic (rounded lat and long)
> >            scale_fill_gradient(name = "Children Reached",           #sets the gradient of the value scale: names the scale
> >                                low = grey_2,                            #color of the low end
> >                                high = orange_1) +                       #color of the high end
> >            expand_limits(x = tract$long,                            #ensure limits include all values for all plots
> >                          y = tract$lat) +
> >            labs(x = NULL,                                           #add labels, no x title
> >                 y = NULL,                                               #no y title
> >                 title = "Number of Children Reached by Province",       #map title
> >                 subtitle = "2017") +                                    #map subtitle
> >            geom_text(data = by_province,                            #add a text layer
> >                      aes(long,                                          #aethetics for the text, x axis
> >                          lat,                                               #y axis
> >                          label = Number,                                    #the value to display
> >                          size=3)) +                                         #size of the text
> >            theme(axis.ticks = element_blank(),                      #theme of the graph, no axis ticks
> >                  axis.text = element_blank(),                           #no axis text
> >                  panel.background = element_blank(),                    #blank background
> >                  panel.border = element_blank())                        #blank border
> >
> > # save as png
> > ggsave(kids_map, file = "kids_map.png", width = 6, height = 4.5, type = "cairo-png”)
> >
> >
> > I have asked this question on stack overflow, and was refered to this answer:
> > https://stackoverflow.com/questions/9441436/ggplot-centered-names-on-a-map
> >
> > The solution there did not fix my problem, though it did get me closer.
> > The solution on that post is using a single vector of labels.
> >
> > My post on stackoverflow has images of my output:
> > https://stackoverflow.com/questions/49118323/labelling-a-map-plotted-with-geom-map
> >
> > [[alternative HTML version deleted]]
> >
> > _______________________________________________
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> > R-sig-Geo at r-project.org
> > https://stat.ethz.ch/mailman/listinfo/r-sig-geo
> >
>
> --
> Roger Bivand
> Department of Economics, Norwegian School of Economics,
> Helleveien 30, N-5045 Bergen, Norway.
> voice: +47 55 95 93 55; e-mail: Roger.Bivand at nhh.no
> http://orcid.org/0000-0003-2392-6140
> https://scholar.google.no/citations?user=AWeghB0AAAAJ&hl=en

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