Choropleth world map with piecewise.categories?

[lgnbhl]

Hi John, Is it possible to create a choropleth world map with a categorical variable using echarts4r?

Here an reproducible example (not working):

cns <- countrycode::codelist$country.name.en
cns <- data.frame(
  country = cns,
  category = sample(LETTERS[1:4], length(cns), replace=TRUE, prob=c(0.1, 0.2, 0.65, 0.05))
)

# is there an argument missing here?
cns |> 
  e_charts(country) |> 
  e_map(category) |> 
  e_visual_map(category)

I was not even able to find an choropleth map in the official Echarts docs.

If not possible, could Leaflet be used as a workaround?

Thanks again for this great package! Felix

[lgnbhl]

According to @helgasoft "ECharts seems to ignore non-numerical categories in piecewise choropleths" (https://github.com/helgasoft/echarty/issues/14).

Is there a way to use characters/factors instead of transforming them into numerical values? The workaround proposed by @helgasoft is also problematic when using the tooltip calling e_tooltip().

For the record here the solution provided by @helgasoft with numerical values:

cns <- countrycode::codelist$country.name.en
cns <- data.frame(
  country = cns,
  # category = sample(LETTERS[1:4], length(cns), replace=TRUE, prob=c(0.1, 0.2, 0.65, 0.05))
  numeric = sample(1:4, length(cns), replace=TRUE, prob=c(0.1, 0.2, 0.65, 0.05))
)
# set colors for categories
colors <- c('#8b0069','#75c165', '#ce5c5c', '#fbc357')
pieces <- lapply(unique(cns$numeric), function(x) { 
  list(value= x, label= LETTERS[x], color= colors[x]) 
})

cns |> 
  e_charts(country) |> 
  e_map(numeric) |> 
  e_visual_map(numeric, type = "piecewise", pieces = pieces)

[lgnbhl]

@helgasoft kindly provided another better solution using the parameter categories with his own R package echarty (https://github.com/helgasoft/echarty/issues/14).

However, I am not able to reproduce this solution using the categories parameter with "echarts4r".

The official Echarts documentation related to categories: https://echarts.apache.org/en/option.html#visualMap-piecewise.categories

library(dplyr)
cns <- countrycode::codelist$country.name.en
cns <- data.frame(
  country = cns,
  category = sample(LETTERS[1:4], length(cns), replace=TRUE, prob=c(0.1, 0.2, 0.65, 0.05))
) |> 
  mutate(numbas= match(category,LETTERS)) |>   # keep them in sync
  relocate(numbas, .after= country) # default Y-axis is the second column
palet <- c('#8b0069','#75c165', '#ce5c5c', '#fbc357')
fmtr <-  htmlwidgets::JS("function (x) { return x.data[0]+'<br>cat: <b>'+x.data[2]; }")

# https://echarts.apache.org/en/option.html#visualMap-piecewise.categories
cns |> 
  e_charts(country) |> 
  e_map(category) |> 
  e_visual_map(category, 
               type = "piecewise", 
               inRange= list(color= palet),
               outOfRange = list(color= 'grey'),
               categories = LETTERS[1:4], # NOT WORKING!!
               dimension = 2) |>
  e_tooltip(formatter = fmtr) # NOT WORKING!!

[lgnbhl]

Here the solution to add the tooltip, given by the developer of the package: https://github.com/JohnCoene/echarts4r/issues/146#issuecomment-871160283