Section 5 Interactive Visualization

Following Part IV of the methodology, we will now create an interactive visualization to represent feelings of anxiety through space in London. This visualization integrates a continuous raster layer of interpolated heart rate values, and point-based personal comments on emotional state.

The following libraries are required for this visualization:

library(leaflet)
library(raster)
library(htmltools)
library(htmlwidgets)

We will begin by reading in the necessary data:

# read in the heart rate raster 
r <- raster("data/smoothed.tif")

# read in the personal comments 
combined <- read.csv('data/final_comments.csv')

Now we will set the colour palettes that we will use to visualize this data.

# colour palette for the raster 
pal_rast <- colorNumeric(c("#FBEC3C", "#F76C52", "#4B056F"), values(r),
                         na.color = "transparent")

# colour palette for the markers 
pal_markers <- colorFactor(c("#8E09DC", "#FBF3A9"), combined$Sentiment)

We will also use some basic HTML to customize the formatting for the labels and popups on our map.

# formatting for the marker popups 
popup_lab <- paste0('<b>Direction of impact on anxiety: </b>', combined$Sentiment, '<br><b>Theme:</b> ', combined$Theme, '<br><b>Note:</b> <i>', combined$ï..Note, '</i>')
  
# formatting for the map title 
map_title <- HTML("Anxiety Levels in London<br>Dec 4-14, 2019")
  
# formatting for the legend title 
legend_title <- HTML("Personal Comments<br>(Impact on anxiety)")

Now we will use the Leaflet package to create our interactive map.

leaflet() %>% 
  # add basemap tiles
  addProviderTiles(providers$Esri.WorldImagery,
                   options = providerTileOptions(opacity = 0.9)) %>%
  # add the anxiety raster
  addRasterImage(r, 
                 colors = pal_rast, 
                 opacity = 0.9, 
                 group = 'Heart Rate') %>%
  
  # add points for the personal comments 
  addCircleMarkers(data=combined,
                   radius=4,
                   lng = ~combined$X_coord, 
                   lat = ~combined$Y_coord, 
                   group = 'Personal Comments',
                   stroke = TRUE, 
                   fillOpacity = 1, 
                   popup=popup_lab, 
                   color = ~pal_markers(combined$Sentiment)) %>%
  
  # Layers control
  addLayersControl(
    overlayGroups = c("Personal Comments", "Heart Rate"),
    options = layersControlOptions(collapsed = TRUE)
  ) %>%
  
  # add legend for the raster values 
  addLegend(pal = pal_rast, 
            values = values(r),
            title = "Heart Rate", 
            opacity = 1, 
            group = 'Heart Rate') %>%
  
  # add legend for the personal comments 
  addLegend(pal = pal_markers, 
            values = combined$Sentiment,
            title = legend_title, 
            opacity = 1,
            group = 'Personal Comments') %>%
  
  # add scale bar to the map 
  addScaleBar(position = "bottomright") %>%
  
  # add title to the map 
  addControl(map_title, position = "bottomleft")

A full page version of this map can be found here.