How to add a leaflet pop up with conditional lines?

Question

I've got this data frame:

country_groups <- structure(list(country_name = c("Australia", "Brazil", "Canada", 
"China", "China", "China", "China", "China", "China", "China", 
"China", "China", "China", "China", "China", "China", "European Patent Office", 
"European Patent Office", "Germany", "India", "India", "India", 
"India", "India", "India", "Japan", "Japan", "Japan", "Korea [Republic of]", 
"Korea [Republic of]", "Korea [Republic of]", "Korea [Republic of]", 
"Korea [Republic of]", "Romania", "Russian Federation", "Russian Federation", 
"Spain", "Taiwan", "Taiwan", "United Kingdom", "United States", 
"United States", "United States", "United States", "United States", 
"United States", "United States", "United States", "United States", 
"United States", "United States", "United States", "World", "World"
), longitude = c(133.775136, -51.92528, -106.346771, 104.195397, 
104.195397, 104.195397, 104.195397, 104.195397, 104.195397, 104.195397, 
104.195397, 104.195397, 104.195397, 104.195397, 104.195397, 104.195397, 
-20.8685430762787, -20.8685430762787, 10.451526, 78.96288, 78.96288, 
78.96288, 78.96288, 78.96288, 78.96288, 138.252924, 138.252924, 
138.252924, 127.766922, 127.766922, 127.766922, 127.766922, 127.766922, 
24.96676, 105.318756, 105.318756, -3.74922, 120.960515, 120.960515, 
-3.435973, -95.712891, -95.712891, -95.712891, -95.712891, -95.712891, 
-95.712891, -95.712891, -95.712891, -95.712891, -95.712891, -95.712891, 
-95.712891, 71.8853560211639, 71.8853560211639), latitude = c(-25.274398, 
-14.235004, 56.130366, 35.86166, 35.86166, 35.86166, 35.86166, 
35.86166, 35.86166, 35.86166, 35.86166, 35.86166, 35.86166, 35.86166, 
35.86166, 35.86166, 48.2343918029004, 48.2343918029004, 51.165691, 
20.593684, 20.593684, 20.593684, 20.593684, 20.593684, 20.593684, 
36.204824, 36.204824, 36.204824, 35.907757, 35.907757, 35.907757, 
35.907757, 35.907757, 45.943161, 61.52401, 61.52401, 40.463667, 
23.69781, 23.69781, 55.378051, 37.09024, 37.09024, 37.09024, 
37.09024, 37.09024, 37.09024, 37.09024, 37.09024, 37.09024, 37.09024, 
37.09024, 37.09024, -51.681674860461, -51.681674860461), topic = c("Population growth", 
"Education", "Arts", "Sports", "Growing plants", "Reading", "Story telling", 
"Gymnastics", "Cooking classes", "Education", "Arts", "Arcade", 
"Acting", "Population growth", "Movies", "Education", "Sports", 
"Arcade", "Movies", "Sports", "Reading", "Gymnastics", "Cooking classes", 
"Education", "Population growth", "Sports", "Reading", "Gymnastics", 
"Growing plants", "Gymnastics", "Arcade", "Acting", "Movies", 
"Gymnastics", "Sports", "Gymnastics", "Arcade", "Gymnastics", 
"Arcade", "Gymnastics", "Sports", "Growing plants", "Reading", 
"Gymnastics", "Cooking classes", "Education", "Arts", "Arcade", 
"Acting", "Population growth", "Movies", "Education", "Arcade", 
"Movies"), n = c(2L, 1L, 1L, 34L, 31L, 51L, 82L, 63L, 22L, 17L, 
43L, 53L, 34L, 43L, 46L, 22L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 
1L, 1L, 1L, 1L, 2L, 1L, 1L, 1L, 1L, 1L, 1L, 2L, 1L, 1L, 2L, 1L, 
4L, 3L, 3L, 23L, 1L, 4L, 2L, 2L, 8L, 2L, 3L, 1L, 1L, 1L)), row.names = c(NA, 
-54L), class = "data.frame")

And I wish to perform leaflet mapping with it, in a way that when you click on the corresponding marker, it displays country name, followed by each TOPIC = NUMBER below. I've had such a hard time because everywhere I've seen they mostly use paste0 or paste and that is able to get the job done. This time each country could have all topics or just one, I've tried to get it done as they do in the official webpage with no luck, It seems simple but I can't get it done, somebody might know how to? Below you can see what coding I use. Thanks in advance!

library(leaflet)
library(dplyr)
# Maping
leaflet(country_groups) %>% 
  addTiles() %>% 
  setView( lng = 0, lat = 0, zoom = 1) %>% 
  addProviderTiles("Esri.WorldTopoMap") %>%
  addMarkers(~longitude, ~latitude, popup = ~HTML(paste0("<br>", "Country:", country_name,"<br/>",
                                                    country_groups %>%  
                                                      filter(country_name %in% country_name) %>% 
                                                      select(topic,n) )))

And this is the kind of pop up I expect (China), but adding the Country name upfront:

country_selec <- country_groups %>% filter(country_name == "China")
country_info <- country_selec[c("topic","n")];names(country_info) <- c("Topic","Count")

This is how it displays with answear provided, it would be perfectly brilliant if it displayed as it does for @Wimpel

Wimpel · Accepted Answer · 2020-02-24T19:59:11.717

I struggled with this in the past too.. Here is my solution:

first, create a helper data.frame, with the values for each country, named df.helper.
Then, create a list with labels ( as a string with html-tags) for each country. Last, build the leaflet, and create the labels using lapply and HTML from the htmltools-package to get nice HTML-code for in the popups.

You can, of course, edit the string inside the paste0-command that creates the custom.labels to suit your desired format. All HTML-tags are permitted, so go nuts ;-)

#load libraries
library(leaflet);library(htmltools)
#create a helper data.frame with a unique country_name in each row                                                                                                                                                                                                                                            -54L), class = "data.frame")
df.helper <- country_groups[ !duplicated( country_groups$country_name),  ]
#create the custom labels by country
custom.labels <- lapply( seq( nrow( df.helper ) ), function(i) {
   paste0( '<p><b>', df.helper[i, "country_name" ], '</b><br></p><p>',
           paste( country_groups[which(country_groups$country_name == df.helper[i, "country_name"]), "topic"],
                  country_groups[which(country_groups$country_name == df.helper[i, "country_name"]), "n"],
                 sep = " - ", collapse="<br>"), 
           '</p>' ) 
})
#create the leaflet
leaflet(df.helper) %>% 
   addTiles() %>% 
   setView( lng = 0, lat = 0, zoom = 1) %>% 
   addProviderTiles("Esri.WorldTopoMap") %>%
   addMarkers(
      lng = ~longitude, 
      lat = ~latitude, 
      popup = lapply( custom.labels, htmltools::HTML ) 
      )

This is just what I need, but it's not working for me :( I don't know how it's supposed to be like, but I'm running it straigth forward and `df.helper` is turning into a data frame with only 16 rows, one per each country and one topic only. Inside `custom.labels` list I can view that only Australia is giving me something (`Population growth - 2`). The remaining countries type the name in strong letters but say `character (0) - integer(0)` below. — MelaniaCB, Feb 25 '20 at 01:14
strange.. I cannot reproduce your results with the sample data provided and code from my answer... Can you try with a fresh R-session, woth only `dplyr`, `leaflet` and `htmltools`-packages loaded? — Wimpel, Feb 25 '20 at 07:59
Turned out it was that R-Session giving me a hard time. Left my laptop off overnight and just turned out as beautiful as it did on your answear. Thank you so so so very much! — MelaniaCB, Feb 25 '20 at 16:13
But it keeps on giving me the same issue when it's inside the shiny App I'm developing, any idea why? :( — MelaniaCB, Feb 25 '20 at 17:31
Just needed to go one by one setting it as character, numeric or data frame depending on the object! Thanks again :) — MelaniaCB, Feb 25 '20 at 18:02

How to add a leaflet pop up with conditional lines?

1 Answers1