How to Make a Map with R

Step 0: Setup R environment

Set working directory for entire markdown file using knitr

Set various values needed, including names of files and FIPS codes for New Hampshire and South Carolina

nhdatafile <- "NHD2016.xlsx"
nhdatafilecsv <- "NHD2016.csv"
usshapefile <- "cb_2014_us_county_5m/cb_2014_us_county_5m.shp"
nhfipscode <- "33"
scdatafile <- "SCGOP2016.csv"
scfipscode <- "45"

Load in packages for entire markdown

library(tidyverse)
library(tmap)
library(tmaptools)
library(leaflet)
library(sf)
library(leaflet.extras)
library(dplyr)
library(rio)
library(sp)
library(raster)
library(rgdal)
library(scales)
library(htmlwidgets)

Step 1: Read in the New Hampshire election results file

nhdata <- import(nhdatafilecsv)

Eliminate columns for minor candidates and just use County, Clinton and Sanders columns

nhdata <- nhdata[,c("County", "Clinton", "Sanders")]

Step 2: Decide what data to map

Add columns for percents and margins

nhdata$SandersMarginVotes <- nhdata$Sanders - nhdata$Clinton
nhdata$SandersPct <- (nhdata$Sanders) / (nhdata$Sanders + nhdata$Clinton) 
nhdata$ClintonPct <- (nhdata$Clinton) / (nhdata$Sanders + nhdata$Clinton)
nhdata$SandersMarginPctgPoints <- nhdata$SandersPct - nhdata$ClintonPct

Step 3: Get geographic data files

Read in the shapefile for US states and counties:

usgeo <- shapefile("cb_2014_us_county_5m/cb_2014_us_county_5m.shp")
## Warning in rgdal::readOGR(dirname(x), fn, stringsAsFactors = stringsAsFactors, :
## Z-dimension discarded

Do a quick plot (qtm = quick thematic map) of the shapefile and check its structure:

qtm(usgeo)

head(usgeo)
##   STATEFP COUNTYFP COUNTYNS       AFFGEOID GEOID        NAME LSAD      ALAND
## 0      01      059 00161555 0500000US01059 01059    Franklin   06 1641580723
## 1      13      111 00351094 0500000US13111 13111      Fannin   06 1002370118
## 2      19      109 00465243 0500000US19109 19109     Kossuth   06 2519332669
## 3      40      115 01101845 0500000US40115 40115      Ottawa   06 1219467406
## 4      42      115 01213688 0500000US42115 42115 Susquehanna   06 2132881515
## 5      40      053 01101814 0500000US40053 40053       Grant   06 2592245098
##     AWATER
## 0 32904833
## 1 13560697
## 2  4154722
## 3 35708892
## 4 22356541
## 5  7021964

Subset the New Hampshire data from the US shapefile

nhgeo <- usgeo[usgeo$STATEFP==nhfipscode,]

Tmap test plot of the New Hampshire data

qtm(nhgeo)

Check the structure of the object

str(nhgeo)
## Formal class 'SpatialPolygonsDataFrame' [package "sp"] with 5 slots
##   ..@ data       :'data.frame':  10 obs. of  9 variables:
##   .. ..$ STATEFP : chr [1:10] "33" "33" "33" "33" ...
##   .. ..$ COUNTYFP: chr [1:10] "009" "011" "007" "001" ...
##   .. ..$ COUNTYNS: chr [1:10] "00873178" "00873179" "00873177" "00873174" ...
##   .. ..$ AFFGEOID: chr [1:10] "0500000US33009" "0500000US33011" "0500000US33007" "0500000US33001" ...
##   .. ..$ GEOID   : chr [1:10] "33009" "33011" "33007" "33001" ...
##   .. ..$ NAME    : chr [1:10] "Grafton" "Hillsborough" "Coos" "Belknap" ...
##   .. ..$ LSAD    : chr [1:10] "06" "06" "06" "06" ...
##   .. ..$ ALAND   : chr [1:10] "4425927252" "2269220216" "4648216798" "1036582289" ...
##   .. ..$ AWATER  : chr [1:10] "105375486" "41604851" "90773891" "177039345" ...
##   ..@ polygons   :List of 10
##   .. ..$ :Formal class 'Polygons' [package "sp"] with 5 slots
##   .. .. .. ..@ Polygons :List of 1
##   .. .. .. .. ..$ :Formal class 'Polygon' [package "sp"] with 5 slots
##   .. .. .. .. .. .. ..@ labpt  : num [1:2] -71.8 43.9
##   .. .. .. .. .. .. ..@ area   : num 0.508
##   .. .. .. .. .. .. ..@ hole   : logi FALSE
##   .. .. .. .. .. .. ..@ ringDir: int 1
##   .. .. .. .. .. .. ..@ coords : num [1:327, 1:2] -72.3 -72.3 -72.3 -72.3 -72.3 ...
##   .. .. .. ..@ plotOrder: int 1
##   .. .. .. ..@ labpt    : num [1:2] -71.8 43.9
##   .. .. .. ..@ ID       : chr "685"
##   .. .. .. ..@ area     : num 0.508
##   .. ..$ :Formal class 'Polygons' [package "sp"] with 5 slots
##   .. .. .. ..@ Polygons :List of 1
##   .. .. .. .. ..$ :Formal class 'Polygon' [package "sp"] with 5 slots
##   .. .. .. .. .. .. ..@ labpt  : num [1:2] -71.7 42.9
##   .. .. .. .. .. .. ..@ area   : num 0.255
##   .. .. .. .. .. .. ..@ hole   : logi FALSE
##   .. .. .. .. .. .. ..@ ringDir: int 1
##   .. .. .. .. .. .. ..@ coords : num [1:45, 1:2] -72.1 -72 -72 -72 -72 ...
##   .. .. .. ..@ plotOrder: int 1
##   .. .. .. ..@ labpt    : num [1:2] -71.7 42.9
##   .. .. .. ..@ ID       : chr "866"
##   .. .. .. ..@ area     : num 0.255
##   .. ..$ :Formal class 'Polygons' [package "sp"] with 5 slots
##   .. .. .. ..@ Polygons :List of 1
##   .. .. .. .. ..$ :Formal class 'Polygon' [package "sp"] with 5 slots
##   .. .. .. .. .. .. ..@ labpt  : num [1:2] -71.3 44.7
##   .. .. .. .. .. .. ..@ area   : num 0.539
##   .. .. .. .. .. .. ..@ hole   : logi FALSE
##   .. .. .. .. .. .. ..@ ringDir: int 1
##   .. .. .. .. .. .. ..@ coords : num [1:511, 1:2] -71.8 -71.8 -71.8 -71.7 -71.7 ...
##   .. .. .. ..@ plotOrder: int 1
##   .. .. .. ..@ labpt    : num [1:2] -71.3 44.7
##   .. .. .. ..@ ID       : chr "922"
##   .. .. .. ..@ area     : num 0.539
##   .. ..$ :Formal class 'Polygons' [package "sp"] with 5 slots
##   .. .. .. ..@ Polygons :List of 1
##   .. .. .. .. ..$ :Formal class 'Polygon' [package "sp"] with 5 slots
##   .. .. .. .. .. .. ..@ labpt  : num [1:2] -71.4 43.5
##   .. .. .. .. .. .. ..@ area   : num 0.136
##   .. .. .. .. .. .. ..@ hole   : logi FALSE
##   .. .. .. .. .. .. ..@ ringDir: int 1
##   .. .. .. .. .. .. ..@ coords : num [1:33, 1:2] -71.7 -71.7 -71.7 -71.7 -71.7 ...
##   .. .. .. ..@ plotOrder: int 1
##   .. .. .. ..@ labpt    : num [1:2] -71.4 43.5
##   .. .. .. ..@ ID       : chr "1100"
##   .. .. .. ..@ area     : num 0.136
##   .. ..$ :Formal class 'Polygons' [package "sp"] with 5 slots
##   .. .. .. ..@ Polygons :List of 1
##   .. .. .. .. ..$ :Formal class 'Polygon' [package "sp"] with 5 slots
##   .. .. .. .. .. .. ..@ labpt  : num [1:2] -71.1 43
##   .. .. .. .. .. .. ..@ area   : num 0.208
##   .. .. .. .. .. .. ..@ hole   : logi FALSE
##   .. .. .. .. .. .. ..@ ringDir: int 1
##   .. .. .. .. .. .. ..@ coords : num [1:123, 1:2] -71.5 -71.4 -71.4 -71.4 -71.4 ...
##   .. .. .. ..@ plotOrder: int 1
##   .. .. .. ..@ labpt    : num [1:2] -71.1 43
##   .. .. .. ..@ ID       : chr "1278"
##   .. .. .. ..@ area     : num 0.208
##   .. ..$ :Formal class 'Polygons' [package "sp"] with 5 slots
##   .. .. .. ..@ Polygons :List of 1
##   .. .. .. .. ..$ :Formal class 'Polygon' [package "sp"] with 5 slots
##   .. .. .. .. .. .. ..@ labpt  : num [1:2] -72.3 42.9
##   .. .. .. .. .. .. ..@ area   : num 0.208
##   .. .. .. .. .. .. ..@ hole   : logi FALSE
##   .. .. .. .. .. .. ..@ ringDir: int 1
##   .. .. .. .. .. .. ..@ coords : num [1:161, 1:2] -72.6 -72.6 -72.6 -72.6 -72.6 ...
##   .. .. .. ..@ plotOrder: int 1
##   .. .. .. ..@ labpt    : num [1:2] -72.3 42.9
##   .. .. .. ..@ ID       : chr "1877"
##   .. .. .. ..@ area     : num 0.208
##   .. ..$ :Formal class 'Polygons' [package "sp"] with 5 slots
##   .. .. .. ..@ Polygons :List of 1
##   .. .. .. .. ..$ :Formal class 'Polygon' [package "sp"] with 5 slots
##   .. .. .. .. .. .. ..@ labpt  : num [1:2] -71 43.3
##   .. .. .. .. .. .. ..@ area   : num 0.11
##   .. .. .. .. .. .. ..@ hole   : logi FALSE
##   .. .. .. .. .. .. ..@ ringDir: int 1
##   .. .. .. .. .. .. ..@ coords : num [1:177, 1:2] -71.2 -71.2 -71.2 -71.2 -71.1 ...
##   .. .. .. ..@ plotOrder: int 1
##   .. .. .. ..@ labpt    : num [1:2] -71 43.3
##   .. .. .. ..@ ID       : chr "2676"
##   .. .. .. ..@ area     : num 0.11
##   .. ..$ :Formal class 'Polygons' [package "sp"] with 5 slots
##   .. .. .. ..@ Polygons :List of 1
##   .. .. .. .. ..$ :Formal class 'Polygon' [package "sp"] with 5 slots
##   .. .. .. .. .. .. ..@ labpt  : num [1:2] -71.7 43.3
##   .. .. .. .. .. .. ..@ area   : num 0.274
##   .. .. .. .. .. .. ..@ hole   : logi FALSE
##   .. .. .. .. .. .. ..@ ringDir: int 1
##   .. .. .. .. .. .. ..@ coords : num [1:49, 1:2] -72.1 -72.1 -72 -72.1 -72.1 ...
##   .. .. .. ..@ plotOrder: int 1
##   .. .. .. ..@ labpt    : num [1:2] -71.7 43.3
##   .. .. .. ..@ ID       : chr "2773"
##   .. .. .. ..@ area     : num 0.274
##   .. ..$ :Formal class 'Polygons' [package "sp"] with 5 slots
##   .. .. .. ..@ Polygons :List of 1
##   .. .. .. .. ..$ :Formal class 'Polygon' [package "sp"] with 5 slots
##   .. .. .. .. .. .. ..@ labpt  : num [1:2] -71.2 43.9
##   .. .. .. .. .. .. ..@ area   : num 0.288
##   .. .. .. .. .. .. ..@ hole   : logi FALSE
##   .. .. .. .. .. .. ..@ ringDir: int 1
##   .. .. .. .. .. .. ..@ coords : num [1:73, 1:2] -71.6 -71.4 -71.4 -71.3 -71.4 ...
##   .. .. .. ..@ plotOrder: int 1
##   .. .. .. ..@ labpt    : num [1:2] -71.2 43.9
##   .. .. .. ..@ ID       : chr "3077"
##   .. .. .. ..@ area     : num 0.288
##   .. ..$ :Formal class 'Polygons' [package "sp"] with 5 slots
##   .. .. .. ..@ Polygons :List of 1
##   .. .. .. .. ..$ :Formal class 'Polygon' [package "sp"] with 5 slots
##   .. .. .. .. .. .. ..@ labpt  : num [1:2] -72.2 43.4
##   .. .. .. .. .. .. ..@ area   : num 0.159
##   .. .. .. .. .. .. ..@ hole   : logi FALSE
##   .. .. .. .. .. .. ..@ ringDir: int 1
##   .. .. .. .. .. .. ..@ coords : num [1:118, 1:2] -72.5 -72.4 -72.4 -72.4 -72.4 ...
##   .. .. .. ..@ plotOrder: int 1
##   .. .. .. ..@ labpt    : num [1:2] -72.2 43.4
##   .. .. .. ..@ ID       : chr "3167"
##   .. .. .. ..@ area     : num 0.159
##   ..@ plotOrder  : int [1:10] 3 1 9 8 2 6 5 10 4 7
##   ..@ bbox       : num [1:2, 1:2] -72.6 42.7 -70.7 45.3
##   .. ..- attr(*, "dimnames")=List of 2
##   .. .. ..$ : chr [1:2] "x" "y"
##   .. .. ..$ : chr [1:2] "min" "max"
##   ..@ proj4string:Formal class 'CRS' [package "sp"] with 1 slot
##   .. .. ..@ projargs: chr "+proj=longlat +datum=NAD83 +no_defs"

Check if county names are in the same format in both files

str(nhgeo$NAME)
##  chr [1:10] "Grafton" "Hillsborough" "Coos" "Belknap" "Rockingham" ...
str(nhdata$County)
##  chr [1:10] "Belknap" "Carroll" "Cheshire" "Coos" "Grafton" "Hillsborough" ...
identical(nhgeo[order(nhgeo$NAME),], nhdata[order(nhdata$County),])
## [1] FALSE

They’re not identical. Change the county names to plain characters in nhgeo

nhgeo$NAME <- as.character(nhgeo$NAME)

Order each data set by county name. Are the two county columns identical now? They should be.

nhgeo <- nhgeo[order(nhgeo$NAME),]
nhdata <- nhdata[order(nhdata$County),]
identical(nhgeo$NAME,nhdata$County)
## [1] TRUE

Step 4: Merge geo data with results data

nhmap <- merge(nhgeo, nhdata, by.x = "NAME", by.y = "County")

Check the new data structure

str(nhmap)
## Formal class 'SpatialPolygonsDataFrame' [package "sp"] with 5 slots
##   ..@ data       :'data.frame':  10 obs. of  15 variables:
##   .. ..$ NAME                   : chr [1:10] "Belknap" "Carroll" "Cheshire" "Coos" ...
##   .. ..$ STATEFP                : chr [1:10] "33" "33" "33" "33" ...
##   .. ..$ COUNTYFP               : chr [1:10] "001" "003" "005" "007" ...
##   .. ..$ COUNTYNS               : chr [1:10] "00873174" "00873175" "00873176" "00873177" ...
##   .. ..$ AFFGEOID               : chr [1:10] "0500000US33001" "0500000US33003" "0500000US33005" "0500000US33007" ...
##   .. ..$ GEOID                  : chr [1:10] "33001" "33003" "33005" "33007" ...
##   .. ..$ LSAD                   : chr [1:10] "06" "06" "06" "06" ...
##   .. ..$ ALAND                  : chr [1:10] "1036582289" "2411458935" "1830366195" "4648216798" ...
##   .. ..$ AWATER                 : chr [1:10] "177039345" "158933434" "57990901" "90773891" ...
##   .. ..$ Clinton                : int [1:10] 3495 3230 5132 2013 6918 28147 12250 22829 8813 2497
##   .. ..$ Sanders                : int [1:10] 6005 5638 12441 3639 14245 39245 18107 31065 15881 5915
##   .. ..$ SandersMarginVotes     : int [1:10] 2510 2408 7309 1626 7327 11098 5857 8236 7068 3418
##   .. ..$ SandersPct             : num [1:10] 0.632 0.636 0.708 0.644 0.673 ...
##   .. ..$ ClintonPct             : num [1:10] 0.368 0.364 0.292 0.356 0.327 ...
##   .. ..$ SandersMarginPctgPoints: num [1:10] 0.264 0.272 0.416 0.288 0.346 ...
##   ..@ polygons   :List of 10
##   .. ..$ :Formal class 'Polygons' [package "sp"] with 5 slots
##   .. .. .. ..@ Polygons :List of 1
##   .. .. .. .. ..$ :Formal class 'Polygon' [package "sp"] with 5 slots
##   .. .. .. .. .. .. ..@ labpt  : num [1:2] -71.4 43.5
##   .. .. .. .. .. .. ..@ area   : num 0.136
##   .. .. .. .. .. .. ..@ hole   : logi FALSE
##   .. .. .. .. .. .. ..@ ringDir: int 1
##   .. .. .. .. .. .. ..@ coords : num [1:33, 1:2] -71.7 -71.7 -71.7 -71.7 -71.7 ...
##   .. .. .. ..@ plotOrder: int 1
##   .. .. .. ..@ labpt    : num [1:2] -71.4 43.5
##   .. .. .. ..@ ID       : chr "1100"
##   .. .. .. ..@ area     : num 0.136
##   .. ..$ :Formal class 'Polygons' [package "sp"] with 5 slots
##   .. .. .. ..@ Polygons :List of 1
##   .. .. .. .. ..$ :Formal class 'Polygon' [package "sp"] with 5 slots
##   .. .. .. .. .. .. ..@ labpt  : num [1:2] -71.2 43.9
##   .. .. .. .. .. .. ..@ area   : num 0.288
##   .. .. .. .. .. .. ..@ hole   : logi FALSE
##   .. .. .. .. .. .. ..@ ringDir: int 1
##   .. .. .. .. .. .. ..@ coords : num [1:73, 1:2] -71.6 -71.4 -71.4 -71.3 -71.4 ...
##   .. .. .. ..@ plotOrder: int 1
##   .. .. .. ..@ labpt    : num [1:2] -71.2 43.9
##   .. .. .. ..@ ID       : chr "3077"
##   .. .. .. ..@ area     : num 0.288
##   .. ..$ :Formal class 'Polygons' [package "sp"] with 5 slots
##   .. .. .. ..@ Polygons :List of 1
##   .. .. .. .. ..$ :Formal class 'Polygon' [package "sp"] with 5 slots
##   .. .. .. .. .. .. ..@ labpt  : num [1:2] -72.3 42.9
##   .. .. .. .. .. .. ..@ area   : num 0.208
##   .. .. .. .. .. .. ..@ hole   : logi FALSE
##   .. .. .. .. .. .. ..@ ringDir: int 1
##   .. .. .. .. .. .. ..@ coords : num [1:161, 1:2] -72.6 -72.6 -72.6 -72.6 -72.6 ...
##   .. .. .. ..@ plotOrder: int 1
##   .. .. .. ..@ labpt    : num [1:2] -72.3 42.9
##   .. .. .. ..@ ID       : chr "1877"
##   .. .. .. ..@ area     : num 0.208
##   .. ..$ :Formal class 'Polygons' [package "sp"] with 5 slots
##   .. .. .. ..@ Polygons :List of 1
##   .. .. .. .. ..$ :Formal class 'Polygon' [package "sp"] with 5 slots
##   .. .. .. .. .. .. ..@ labpt  : num [1:2] -71.3 44.7
##   .. .. .. .. .. .. ..@ area   : num 0.539
##   .. .. .. .. .. .. ..@ hole   : logi FALSE
##   .. .. .. .. .. .. ..@ ringDir: int 1
##   .. .. .. .. .. .. ..@ coords : num [1:511, 1:2] -71.8 -71.8 -71.8 -71.7 -71.7 ...
##   .. .. .. ..@ plotOrder: int 1
##   .. .. .. ..@ labpt    : num [1:2] -71.3 44.7
##   .. .. .. ..@ ID       : chr "922"
##   .. .. .. ..@ area     : num 0.539
##   .. ..$ :Formal class 'Polygons' [package "sp"] with 5 slots
##   .. .. .. ..@ Polygons :List of 1
##   .. .. .. .. ..$ :Formal class 'Polygon' [package "sp"] with 5 slots
##   .. .. .. .. .. .. ..@ labpt  : num [1:2] -71.8 43.9
##   .. .. .. .. .. .. ..@ area   : num 0.508
##   .. .. .. .. .. .. ..@ hole   : logi FALSE
##   .. .. .. .. .. .. ..@ ringDir: int 1
##   .. .. .. .. .. .. ..@ coords : num [1:327, 1:2] -72.3 -72.3 -72.3 -72.3 -72.3 ...
##   .. .. .. ..@ plotOrder: int 1
##   .. .. .. ..@ labpt    : num [1:2] -71.8 43.9
##   .. .. .. ..@ ID       : chr "685"
##   .. .. .. ..@ area     : num 0.508
##   .. ..$ :Formal class 'Polygons' [package "sp"] with 5 slots
##   .. .. .. ..@ Polygons :List of 1
##   .. .. .. .. ..$ :Formal class 'Polygon' [package "sp"] with 5 slots
##   .. .. .. .. .. .. ..@ labpt  : num [1:2] -71.7 42.9
##   .. .. .. .. .. .. ..@ area   : num 0.255
##   .. .. .. .. .. .. ..@ hole   : logi FALSE
##   .. .. .. .. .. .. ..@ ringDir: int 1
##   .. .. .. .. .. .. ..@ coords : num [1:45, 1:2] -72.1 -72 -72 -72 -72 ...
##   .. .. .. ..@ plotOrder: int 1
##   .. .. .. ..@ labpt    : num [1:2] -71.7 42.9
##   .. .. .. ..@ ID       : chr "866"
##   .. .. .. ..@ area     : num 0.255
##   .. ..$ :Formal class 'Polygons' [package "sp"] with 5 slots
##   .. .. .. ..@ Polygons :List of 1
##   .. .. .. .. ..$ :Formal class 'Polygon' [package "sp"] with 5 slots
##   .. .. .. .. .. .. ..@ labpt  : num [1:2] -71.7 43.3
##   .. .. .. .. .. .. ..@ area   : num 0.274
##   .. .. .. .. .. .. ..@ hole   : logi FALSE
##   .. .. .. .. .. .. ..@ ringDir: int 1
##   .. .. .. .. .. .. ..@ coords : num [1:49, 1:2] -72.1 -72.1 -72 -72.1 -72.1 ...
##   .. .. .. ..@ plotOrder: int 1
##   .. .. .. ..@ labpt    : num [1:2] -71.7 43.3
##   .. .. .. ..@ ID       : chr "2773"
##   .. .. .. ..@ area     : num 0.274
##   .. ..$ :Formal class 'Polygons' [package "sp"] with 5 slots
##   .. .. .. ..@ Polygons :List of 1
##   .. .. .. .. ..$ :Formal class 'Polygon' [package "sp"] with 5 slots
##   .. .. .. .. .. .. ..@ labpt  : num [1:2] -71.1 43
##   .. .. .. .. .. .. ..@ area   : num 0.208
##   .. .. .. .. .. .. ..@ hole   : logi FALSE
##   .. .. .. .. .. .. ..@ ringDir: int 1
##   .. .. .. .. .. .. ..@ coords : num [1:123, 1:2] -71.5 -71.4 -71.4 -71.4 -71.4 ...
##   .. .. .. ..@ plotOrder: int 1
##   .. .. .. ..@ labpt    : num [1:2] -71.1 43
##   .. .. .. ..@ ID       : chr "1278"
##   .. .. .. ..@ area     : num 0.208
##   .. ..$ :Formal class 'Polygons' [package "sp"] with 5 slots
##   .. .. .. ..@ Polygons :List of 1
##   .. .. .. .. ..$ :Formal class 'Polygon' [package "sp"] with 5 slots
##   .. .. .. .. .. .. ..@ labpt  : num [1:2] -71 43.3
##   .. .. .. .. .. .. ..@ area   : num 0.11
##   .. .. .. .. .. .. ..@ hole   : logi FALSE
##   .. .. .. .. .. .. ..@ ringDir: int 1
##   .. .. .. .. .. .. ..@ coords : num [1:177, 1:2] -71.2 -71.2 -71.2 -71.2 -71.1 ...
##   .. .. .. ..@ plotOrder: int 1
##   .. .. .. ..@ labpt    : num [1:2] -71 43.3
##   .. .. .. ..@ ID       : chr "2676"
##   .. .. .. ..@ area     : num 0.11
##   .. ..$ :Formal class 'Polygons' [package "sp"] with 5 slots
##   .. .. .. ..@ Polygons :List of 1
##   .. .. .. .. ..$ :Formal class 'Polygon' [package "sp"] with 5 slots
##   .. .. .. .. .. .. ..@ labpt  : num [1:2] -72.2 43.4
##   .. .. .. .. .. .. ..@ area   : num 0.159
##   .. .. .. .. .. .. ..@ hole   : logi FALSE
##   .. .. .. .. .. .. ..@ ringDir: int 1
##   .. .. .. .. .. .. ..@ coords : num [1:118, 1:2] -72.5 -72.4 -72.4 -72.4 -72.4 ...
##   .. .. .. ..@ plotOrder: int 1
##   .. .. .. ..@ labpt    : num [1:2] -72.2 43.4
##   .. .. .. ..@ ID       : chr "3167"
##   .. .. .. ..@ area     : num 0.159
##   ..@ plotOrder  : int [1:10] 4 5 2 7 6 3 8 10 1 9
##   ..@ bbox       : num [1:2, 1:2] -72.6 42.7 -70.7 45.3
##   .. ..- attr(*, "dimnames")=List of 2
##   .. .. ..$ : chr [1:2] "x" "y"
##   .. .. ..$ : chr [1:2] "min" "max"
##   ..@ proj4string:Formal class 'CRS' [package "sp"] with 1 slot
##   .. .. ..@ projargs: chr "+proj=longlat +datum=NAD83 +no_defs"

Step 5: Create a static map with tmap’s qtm() function

qtm(nhmap, "SandersMarginVotes")
## Some legend labels were too wide. These labels have been resized to 0.63, 0.63, 0.63, 0.58, 0.54. Increase legend.width (argument of tm_layout) to make the legend wider and therefore the labels larger.

qtm(nhmap, "SandersMarginPctgPoints")

Use the tm_shape() function for more control over look and feel.

tm_shape(nhmap) +
  tm_fill("SandersMarginVotes", title="Sanders Margin, Total Votes", palette = "PRGn") +
  tm_borders(alpha=.5) +
  tm_text("NAME", size=0.8)
## Warning in sp::proj4string(obj): CRS object has comment, which is lost in output
## Some legend labels were too wide. These labels have been resized to 0.63, 0.63, 0.63, 0.58, 0.54. Increase legend.width (argument of tm_layout) to make the legend wider and therefore the labels larger.

Store the static map in a variable, and change the theme to “classic” style.

nhstaticmap <- tm_shape(nhmap) +
tm_fill("SandersMarginVotes", title="Sanders Margin, Total Votes", palette = "viridis") + 
tm_borders(alpha=.5) +
tm_text("NAME", size=0.8) + 
tm_style("classic")

View the map.

nhstaticmap
## Warning in sp::proj4string(obj): CRS object has comment, which is lost in output
## Some legend labels were too wide. These labels have been resized to 0.63, 0.63, 0.63, 0.58, 0.54. Increase legend.width (argument of tm_layout) to make the legend wider and therefore the labels larger.

Save the map to a jpg file with tmap’s tmap_save()

tmap_save(nhstaticmap, filename="nhdemprimary.jpg") 
## Warning in sp::proj4string(obj): CRS object has comment, which is lost in output

## Warning in sp::proj4string(obj): CRS object has comment, which is lost in output
## Map saved to /Users/benfeard/Desktop/Data Science/Data Science 110/Week 10/GIS/nhdemprimary.jpg
## Resolution: 1501.336 by 2937.385 pixels
## Size: 5.004452 by 9.791282 inches (300 dpi)

Step 6: Code for an interactive map of Clinton percentages in New Hampshire

Create a palette

clintonPalette <- colorNumeric(palette = "Blues", domain=nhmap$ClintonPct)

Create a pop-up window

nhpopup <- paste0("County: ", nhmap$County,
"Sanders ", percent(nhmap$SandersPct), " - Clinton ", percent(nhmap$ClintonPct))

Step 7: Generate the interactive map

  nhmap_projected <- sp::spTransform(nhmap, "+proj=longlat +datum=WGS84")
leaflet(nhmap_projected) %>%
  addProviderTiles("CartoDB.Positron") %>%
  addPolygons(stroke=FALSE, 
              smoothFactor = 0.2, 
              fillOpacity = .8, 
              popup=nhpopup, 
              color= ~clintonPalette(nhmap$ClintonPct)
  )

Import South Carolina data

scdata <- rio::import(scdatafile)

Import South Carolina shapefile and quick plot of scgeo South Carolina geospatial object

scgeo <- usgeo[usgeo@data$STATEFP=="45",]
qtm(scgeo)

Add a column with percent of votes for each candidate. Candidates are in columns 2-7.

candidates <- colnames(scdata[2:7])
for(i in 2:7){
  j = i + 7
  temp <- scdata[[i]] / scdata$Total
  scdata[[j]] <- temp
  colnames(scdata)[j] <- paste0(colnames(scdata)[i], "Pct")
}  
winner <- colnames(scdata[2:7])

Get winner in each precinct

for(i in 1:nrow(scdata)){
  scdata$winner[i] <- names(which.max(scdata[i,2:7]))
}

Import spreadsheet with percent of adult population holding at least a 4-yr college degree

sced <- rio::import("SCdegree.xlsx")

Check if county names are in the same format in both files

str(scgeo$NAME)
##  chr [1:46] "Edgefield" "Lee" "Horry" "Allendale" "Marion" "Dorchester" ...
str(scdata$County)
##  chr [1:46] "Abbeville" "Aiken" "Allendale" "Anderson" "Bamberg" "Barnwell" ...
# Change the county names to plain characters in scgeo
scgeo$NAME <- as.character(scgeo$NAME)

# Order each data set by county name
scgeo <- scgeo[order(scgeo$NAME),]
scdata <- scdata[order(scdata$County),]

# Are the two county columns identical now?
identical(scgeo$NAME,scdata$County )
## [1] TRUE

Add the election results and rename county column

scmap <- merge(scgeo, scdata, by.x = "NAME", by.y = "County") 

Step 8: Add palettes for a multi-layer map

Color winner by strength of win with multiple layers. Use same intensity for all - get minimum and maximum for the top 3 combined

minpct <- min(c(scdata$`Donald J TrumpPct`, scdata$`Marco RubioPct`, scdata$`Ted CruzPct`))
maxpct <- max(c(scdata$`Donald J TrumpPct`, scdata$`Marco RubioPct`, scdata$`Ted CruzPct`))

Create leaflet palettes for each layer of the map.

trumpPalette <- colorNumeric(palette = "Purples", domain=c(minpct, maxpct))
rubioPalette <- colorNumeric(palette = "Reds", domain = c(minpct, maxpct))
cruzPalette <- colorNumeric(palette = "Oranges", domain = c(minpct, maxpct))

winnerPalette <- colorFactor(palette=c("#984ea3", "#e41a1c"), domain = scmap$winner)
edPalette <- colorNumeric(palette = "Blues", domain=scmap$PctCollegeDegree)

Create a pop-up.

scpopup <- paste0("<b>County: ", scmap$NAME, "<br />Winner: ", scmap$winner, "</b><br /><br />Trump: ", percent(scmap$`Donald J TrumpPct`), "<br />Rubio: ", percent(scmap$`Marco RubioPct`), "<br />Cruz: ", percent(scmap$`Ted CruzPct`), "<br /><br />Pct w college ed: ", sced$PctCollegeDegree, "% vs state-wide avg of 25%")

Add the projection. *The WGS84 is for World Geodesic System 1984 and it gives a coordinate pair as well as a reference datum

scmap <- sp::spTransform(scmap, "+proj=longlat +datum=WGS84")

Create interactive map showing winner in each county

leaflet(scmap) %>%
  addProviderTiles("CartoDB.Positron") %>%
  addPolygons(stroke=TRUE,
              weight=1,
              smoothFactor = 0.2,
              fillOpacity = .75,
              popup=scpopup, 
              color= ~winnerPalette(scmap$winner),
              group="Winners" ) %>%
    addLegend(position="bottomleft", colors=c("#984ea3", "#e41a1c"), labels=c("Trump", "Rubio"))

Step 9: Add map layers and controls

Put top 3 candidates in their own layers and add education layer then store in scGOPmap variable.

scGOPmap <- leaflet(scmap) %>%
  addProviderTiles("CartoDB.Positron") %>%
  addPolygons(stroke=TRUE,
              weight=1,
              smoothFactor = 0.2,
              fillOpacity = .75,
              popup=scpopup, 
              color= ~winnerPalette(scmap$winner),
              group="Winners"  ) %>% 
    addLegend(position="bottomleft", colors=c("#984ea3", "#e41a1c"), labels=c("Trump", "Rubio"))  %>%

  addPolygons(stroke=TRUE,
     weight=1,
     smoothFactor = 0.2, 
     fillOpacity = .75, 
     popup=scpopup, 
     color= ~trumpPalette(scmap$`Donald J TrumpPct`),
     group="Trump") %>%

  addPolygons(stroke=TRUE,
              weight=1,
              smoothFactor = 0.2, 
              fillOpacity = .75, 
              popup=scpopup, 
              color= ~rubioPalette(scmap$`Marco RubioPct`),
              group="Rubio") %>%

  addPolygons(stroke=TRUE,
              weight=1,
              smoothFactor = 0.2, 
              fillOpacity = .75, 
              popup=scpopup, 
              color= ~cruzPalette(scmap$`Ted CruzPct`),
              group="Cruz") %>%

  addPolygons(stroke=TRUE,
              weight=1,
              smoothFactor = 0.2, 
              fillOpacity = .75, 
              popup=scpopup, 
              color= ~edPalette(sced$PctCollegeDegree),
              group="College degs") %>%

  addLayersControl(
      baseGroups=c("Winners", "Trump", "Rubio", "Cruz", "College degs"),
      position = "bottomleft",
      options = layersControlOptions(collapsed = FALSE))

scGOPmap

Step 10: Save your interactive map

Save as a self-contained HTML file

saveWidget(scGOPmap, file="scGOPwidget.html")

# save as an HTML file with dependencies in another directory:
#saveWidget(widget=scGOPmap, file="scGOPprimary_withdependencies.html", selfcontained=FALSE, libdir = "js")