How to solve "Error: Fill argument neither colors nor valid variable name(s)" in R?

Question

I have an error in my codes which is: Error: Fill argument neither colors nor valid variable name(s)

In the following, I describe how I get this error. Indeed, I have two sets of data and assigned them into two variables named Caifornia_shp and Houses. The information of these two variables are as follow:

head(California_shp)
       NAME
1   Alameda
2    Alpine
3    Amador
4     Butte
5 Calaveras
6    Colusa

head(Houses)
  houseValue income houseAge rooms bedrooms population households latitude longitude
1     452600 8.3252       41   880      129        322        126    37.88   -122.23
2     358500 8.3014       21  7099     1106       2401       1138    37.86   -122.22
3     352100 7.2574       52  1467      190        496        177    37.85   -122.24
4     341300 5.6431       52  1274      235        558        219    37.85   -122.25
5     342200 3.8462       52  1627      280        565        259    37.85   -122.25
6     269700 4.0368       52   919      213        413        193    37.85   -122.25

I merged Houses and California_shp using the following codes:

pts.poly <- point.in.poly(Houses,California_shp)

head(pts.poly@data)

houseValue income houseAge rooms bedrooms population households latitude longitude
1     452600 8.3252       41   880      129        322        126    37.88   -122.23
2     358500 8.3014       21  7099     1106       2401       1138    37.86   -122.22
3     352100 7.2574       52  1467      190        496        177    37.85   -122.24
4     341300 5.6431       52  1274      235        558        219    37.85   -122.25
5     342200 3.8462       52  1627      280        565        259    37.85   -122.25
6     269700 4.0368       52   919      213        413        193    37.85   -122.25
     NAME
1 Alameda
2 Alameda
3 Alameda
4 Alameda
5 Alameda
6 Alameda

head(tapply(pts.poly@data$houseValue,list(pts.poly@data$NAME),mean))
  Alameda    Alpine    Amador     Butte Calaveras    Colusa 
208747.39 118700.00 117146.43  89611.54 107893.75  77731.25

When I want to draw a thematic map by codes:

tm_shape(California_shp)+tm_borders("Blue",lwd = 2)+tm_fill("houseValue")

I get the following error:

Error: Fill argument neither colors nor valid variable name(s)

How can I solve this error?

Answer 1

Find a reprex here. Since you didn't provide the data I used mock data to try to put together a solution.

Note also that the solution is based on the sf package, while your objects are on sp. You can convert sp to sf using st_as_sf().

Also, if you are a beginner I would recommend you to stick to sf unless you really need to work on sp:

library(tigris)
#> To enable 
#> caching of data, set `options(tigris_use_cache = TRUE)` in your R script or .Rprofile.
library(sf)
#> Linking to GEOS 3.9.0, GDAL 3.2.1, PROJ 7.2.1
library(tmap)
library(dplyr)
#> 
#> Attaching package: 'dplyr'
#> The following objects are masked from 'package:stats':
#> 
#>     filter, lag
#> The following objects are masked from 'package:base':
#> 
#>     intersect, setdiff, setequal, union

# Use sf from tigris
California_shp <- counties("California")

Houses <- structure(list(
  houseValue = c(
    452600L, 358500L, 352100L, 341300L,
    342200L, 269700L
  ), income = c(
    8.3252, 8.3014, 7.2574, 5.6431,
    3.8462, 4.0368
  ), houseAge = c(41L, 21L, 52L, 52L, 52L, 52L),
  rooms = c(880L, 7099L, 1467L, 1274L, 1627L, 919L), bedrooms = c(
    129L,
    1106L, 190L, 235L, 280L, 213L
  ), population = c(
    322L, 2401L,
    496L, 558L, 565L, 413L
  ), households = c(
    126L, 1138L, 177L,
    219L, 259L, 193L
  ), latitude = c(
    37.88, 37.86, 37.85, 37.85,
    37.85, 37.85
  ), longitude = c(
    -122.23, -122.22, -122.24, -122.25,
    -122.25, -122.25
  )
), row.names = c(NA, 6L), class = "data.frame")

# Convert Houses to sf
Houses <- st_as_sf(Houses, coords = c("longitude", "latitude"), crs = st_crs(4326))

# Transform both shapes to same CRS
California_shp <- st_transform(California_shp, st_crs(Houses))

# Join points to identify county, transform to dataframe and create mean
pts.poly <- st_join(Houses, California_shp) %>%
  st_drop_geometry() %>%
  group_by(COUNTYFP) %>%
  summarise(houseValue = mean(houseValue))


# Join the newly created dataframe to shape by common variable
California_shp_end <- California_shp %>% left_join(pts.poly, by = "COUNTYFP")

# Plot


tm_shape(California_shp_end) +
  tm_borders("Blue", lwd = 2) +
  tm_fill("houseValue")

^{Created on 2021-06-18 by the reprex package (v2.0.0)}