Map overlay

[rb643]

Perhaps not an issue more a suggestion for an add-on:

Would it be possible to overlay multiple maps? 1.For example say I have a map of beta values for a given analysis that I plot with high transparency and then overlay a thresholded version of the map highlighting the significant regions?

2. Alternatively, would it be possible to add an outline feature that would allow me to thicken the boarders of specific regions?

[drmowinckels]

Hi.

Both these things are possible to achieve with ggseg. Since ggseg is a wrapper for geom_polygon from ggplot2, you can control outline (colour?) and opacity (alpha) either by setting them to a single value (outside mapping = aes()) or using columns in the data to these instead (from within mapping = aes()).

library(ggseg)
#> Loading required package: ggplot2
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

test_data <- dk %>% 
  slice(1:4) %>% 
  select(region, hemi) %>% 
  mutate(tvalue = c(0.5, 2.5, 6.0, 1.0),
         sig = ifelse(tvalue > 2.3, "sig", NA),
         sig_a = ifelse(tvalue > 2.3, 1, .5))

test_data  
#> # A tibble: 4 x 5
#>   region                 hemi  tvalue sig   sig_a
#>   <chr>                  <chr>  <dbl> <chr> <dbl>
#> 1 superior temporal      left     0.5 <NA>    0.5
#> 2 pre central            left     2.5 sig     1  
#> 3 post central           left     6   sig     1  
#> 4 rostral middle frontal left     1   <NA>    0.5

ggseg(.data = test_data, atlas = dk, 
      mapping = aes(fill = tvalue, 
                    colour = sig),
      size = 1) +
  scale_color_discrete(na.value = "transparent")

ggseg(.data = test_data, atlas = dk, 
      mapping = aes(fill = tvalue, 
                    alpha = sig_a)) +
  scale_alpha_identity()

^{Created on 2020-03-18 by the reprex package (v0.3.0)}

[rb643]

Great! Thanks for the quick response!