help creating choropleth map?

[ignacio82]

My data looks like this:

states <-
  structure(
    list(
      State = c(
        "CA", "TX", "IL", "FL", "NY", "OH",
        "NJ", "GA", "MI", "PA", "MA", "CO", "AZ", "NC", "VA", "WA", "IN",
        "MD", "MN", "WI", "MO", "TN", "IA", "KY", "LA", "SC", "CT", "AL",
        "KS", "OR", "OK", "AR", "NV", "UT", "NE", "ID", "MS", "DC", "NM",
        "NH", "ME", "AK", "RI", "MT", "HI", "WV", "SD", "ND", "DE", "VT",
        "WY", "PR", "GU", "VI", "MP", "AS", "na", "MH", "FM", "PW"
      ),
      count = c(
        1590533L, 1016328L, 754535L, 742603L, 714205L,
        538719L, 477278L, 452064L, 437162L, 428616L, 420332L, 391084L,
        380853L, 354601L, 342533L, 335505L, 294670L, 286026L, 273427L,
        246172L, 238968L, 236037L, 235030L, 209514L, 199013L, 191707L,
        185521L, 179931L, 163477L, 159862L, 142610L, 136006L, 120111L,
        117338L, 112671L, 106176L, 102564L, 100168L, 97496L, 69881L,
        69508L, 68684L, 65631L, 62109L, 61123L, 57300L, 57254L, 56091L,
        51696L, 33944L, 32136L, 4822L, 598L, 468L, 49L, 19L, 17L,
        11L, 2L, 1L
      )
    ), .Names = c("State", "count"), class = c("tbl_dt",
                                               "tbl", "data.table", "data.frame"), row.names = c(NA,-60L), .internal.selfref = <
      pointer:0x0000000000320788 >
  )

I would like to create a map of the US using count to color each state. I can create a map of the US with this code:

library(leaflet)
library(maps)
mapStates = map("state", fill = TRUE, plot = FALSE)
leaflet(data = mapStates) %>% addTiles() %>%
  addPolygons(fillColor = topo.colors(10, alpha = NULL), stroke = FALSE)

but, I'm not sure how to change that code to tell it to use my data to color the states.

Thanks for the help!

[chris-holcomb]

The first example @ https://rstudio.github.io/leaflet/shapes.html shows you how to do this.

?leaflet leads to:
"data
a data object (currently supported objects are matrices, data frames, and spatial objects from the sp package of classes SpatialPoints, SpatialPointsDataFrame, Polygon, Polygons, SpatialPolygons, SpatialPolygonsDataFrame, Line, Lines, SpatialLines, and SpatialLinesDataFrame)"

But you are sending class(mapStates) = "map" to leaflet. Maybe there's a way to convert it but I don't see why when you can find anything in maps in a more standard format. FWIW, you probably should just use data.frame instead of structure. In that example, after making sure your states$count lines up with the data used in that example, you would just replace states$AWATER with states$count.

[ignacio82]

I am able to follow the example and create a map of the US (I only had to change 2013 for 2014)

library(rgdal)
library(leaflet)

# From https://www.census.gov/geo/maps-data/data/cbf/cbf_state.html
states <- readOGR(dsn = "./cb_2014_us_state_20m.shp",
                  layer = "cb_2014_us_state_20m", verbose = FALSE)

neStates <- subset(states, states$STUSPS %in% c(
  "CT","ME","MA","NH","RI","VT","NY","NJ","PA"
))

leaflet(states) %>%
  addPolygons(
    stroke = FALSE, fillOpacity = 0.5, smoothFactor = 0.5,
    color = ~colorQuantile("YlOrRd", states$AWATER)(AWATER)
  ) 

What I am not sure is how to change the data to use my_counts$counts instead of states$AWATER
This is the data frame i want to use:

my_counts <- data.frame(
  State = c(
    "CA", "TX", "IL", "FL", "NY", "OH",
    "NJ", "GA", "MI", "PA", "MA", "CO", "AZ", "NC", "VA", "WA", "IN",
    "MD", "MN", "WI", "MO", "TN", "IA", "KY", "LA", "SC", "CT", "AL",
    "KS", "OR", "OK", "AR", "NV", "UT", "NE", "ID", "MS", "DC", "NM",
    "NH", "ME", "AK", "RI", "MT", "HI", "WV", "SD", "ND", "DE", "VT",
    "WY", "PR", "GU", "VI", "MP", "AS", "na", "MH", "FM", "PW"
  ),
  count = c(
    1590533L, 1016328L, 754535L, 742603L, 714205L,
    538719L, 477278L, 452064L, 437162L, 428616L, 420332L, 391084L,
    380853L, 354601L, 342533L, 335505L, 294670L, 286026L, 273427L,
    246172L, 238968L, 236037L, 235030L, 209514L, 199013L, 191707L,
    185521L, 179931L, 163477L, 159862L, 142610L, 136006L, 120111L,
    117338L, 112671L, 106176L, 102564L, 100168L, 97496L, 69881L,
    69508L, 68684L, 65631L, 62109L, 61123L, 57300L, 57254L, 56091L,
    51696L, 33944L, 32136L, 4822L, 598L, 468L, 49L, 19L, 17L,
    11L, 2L, 1L
  )
)

Thanks a lot @cholcomb !

[jcheng5]

Try using sp::merge to combine states with my_counts. http://www.inside-r.org/packages/cran/sp/docs/merge

[mbacou]

@ignacio82 this has in fact nothing to do with leaflet, but here is an example of how to work with SpatialPolygonsDataFrame attribute tables.

# Use data.table or dplyr as you prefer
library(data.table)
states <- readOGR("./cb_2014_us_state_500k", "cb_2014_us_state_500k")

# Make a copy of the SPDF attribute table, and then work normally, as with any data.frame/data.table object
states.dt <- data.table(states@data)
# Create an explicit attribute to keep polygons IDs (useful to "re-attach" the table to the polygons later)
states.dt[, rn := row.names(states)]

my_counts <- data.table(
  State = c(
    "CA", "TX", "IL", "FL", "NY", "OH",
    "NJ", "GA", "MI", "PA", "MA", "CO", "AZ", "NC", "VA", "WA", "IN",
    "MD", "MN", "WI", "MO", "TN", "IA", "KY", "LA", "SC", "CT", "AL",
    "KS", "OR", "OK", "AR", "NV", "UT", "NE", "ID", "MS", "DC", "NM",
    "NH", "ME", "AK", "RI", "MT", "HI", "WV", "SD", "ND", "DE", "VT",
    "WY", "PR", "GU", "VI", "MP", "AS", "na", "MH", "FM", "PW"
  ),
  count = c(
    1590533L, 1016328L, 754535L, 742603L, 714205L,
    538719L, 477278L, 452064L, 437162L, 428616L, 420332L, 391084L,
    380853L, 354601L, 342533L, 335505L, 294670L, 286026L, 273427L,
    246172L, 238968L, 236037L, 235030L, 209514L, 199013L, 191707L,
    185521L, 179931L, 163477L, 159862L, 142610L, 136006L, 120111L,
    117338L, 112671L, 106176L, 102564L, 100168L, 97496L, 69881L,
    69508L, 68684L, 65631L, 62109L, 61123L, 57300L, 57254L, 56091L,
    51696L, 33944L, 32136L, 4822L, 598L, 468L, 49L, 19L, 17L,
    11L, 2L, 1L
  )
)

# Index the 2 data.tables on their common keys and join them
setkey(states.dt, STUSPS)
setkey(my_counts, State)
states.dt <- my_counts[states.dt]

# Re-attach the attribute table to the SPDF
setkey(states.dt, rn)
states@data <- data.frame(states.dt[row.names(states)])
# Make sure polygons IDs and data.frame row.names match
states <- spChFIDs(states, states$rn)

# Create map as usual...

[ignacio82]

Thanks a lot!