# Radial bar charts in R using Plotly

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Creating a radial barchart is fairly easy using plotly. In this post we’ll focus on modifying a radial line chart to make it look like a bar chart so come up with a nice visualization for CO_{2} emissions.

The visualization is inspired by this awesome chart.

# inspired by # https://s-media-cache-ak0.pinimg.com/736x/22/1a/d0/221ad079e362ba13969b1bef30b6a5f2.jpg library(plotly) # read in data df <- read.csv("https://cdn.rawgit.com/plotly/datasets/master/Emissions%20Data.csv", stringsAsFactors = F) # Show only 2011 values df <- subset(df, Year == "2011") # Arrange in increasing order of emissions df <- df %>% dplyr::arrange(Emission) df <- df[-(1:50),] # Add colors colors <- RColorBrewer::brewer.pal(length(unique(df$Continent)), "Spectral") continent <- unique(df$Continent) df$colors <- df$Continent for(i in 1:length(continent)){ idx <- df$colors %in% continent[i] df$colors[idx] <- colors[i] } # Get incremental angle value n <- nrow(df) + 20 dtheta <- 2*pi / n theta <- pi / 2 # Initialise x.coord <- c() y.coord <- c() cols <- c() # This is for the white - circle in the middle adjust <- 20 # Initialize plot p <- plot_ly() for(ctr in 1:nrow(df)){ a <- df$Emission[ctr] + adjust x1 <- adjust * cos(theta) y1 <- adjust * sin(theta) x2 <- a * cos(theta) y2 <- a * sin(theta) x.coord <- c(x.coord, x1, x2, NA) y.coord <- c(y.coord, y1, y2, NA) cols <- c(cols, df$Continent[ctr], df$Continent[ctr], NA) theta <- theta + dtheta p <- add_trace(p, x = c(x1, x2), y = c(y1, y2), mode = "lines", line = list(width = 5, color = df$colors[ctr]), evaluate = T) } # Keep x and y axis extents the same up <- max(na.omit(c(x.coord, y.coord))) + 10 down <- min(na.omit(c(y.coord, y.coord))) - 10 # Add layout options, shapes etc p <- layout(p, showlegend = F, xaxis = list(range = c(down, up), domain = c(0, 0.5), title = "", showgrid = F, zeroline = F, showticklabels = F), yaxis = list(range = c(down, up), title = "", showgrid = F, zeroline = F, showticklabels = F), shapes = list( list(type = "circle", x0 = (-5 - adjust), y0 = (-5 - adjust), x1 = (5 + adjust), y1 = (5 + adjust), fillcolor = "transparent", line = list(color = "white", width = 2)), list(type = "circle", x0 = (-15 - adjust), y0 = (-15 - adjust), x1 = (15 + adjust), y1 = (15 + adjust), fillcolor = "transparent", line = list(color = "white", width = 2)), list(type = "circle", x0 = (-25 - adjust), y0 = (-25 - adjust), x1 = (25 + adjust), y1 = (25 + adjust), fillcolor = "transparent", line = list(color = "white", width = 2)), list(type = "circle", x0 = (-35 - adjust), y0 = (-35 - adjust), x1 = (35 + adjust), y1 = (35 + adjust), fillcolor = "transparent", line = list(color = "white", width = 2)))) # Add annotations for country names p <- plotly_build(p) theta <- pi / 2 textangle <- 90 for(ctr in 1:nrow(df)){ a <- df$Emission[ctr] + adjust a <- a + a/12 x <- a * cos(theta) y <- a * sin(theta) if(ctr < 51) {xanchor <- "right"; yanchor <- "bottom"} if(ctr > 51 & ctr < 84) {xanchor <- "right"; yanchor <- "top"} if(ctr > 84) {xanchor <- "left"; yanchor <- "top"} p$layout$annotations[[ctr]] <- list(x = x, y = y, showarrow = F, text = paste0(df$Country[ctr]), textangle = textangle, xanchor = xanchor, yanchor = yanchor, font = list(family = "serif", size = 9), borderpad = 0, borderwidth = 0) theta <- theta + dtheta textangle <- textangle - (180 / pi * dtheta) if(textangle < -90) textangle <- 90 } # Titles and some other details p$layout$annotations[[148]] <- list(xref = "paper", yref = "paper", x = 0, y = 1, showarrow = F, xanxhor = "left", yanchor = "top", align = "left", text = "Carbon dioxide emissions^{(metric tons per capita)}", font = list(size = 25, color = "black")) p$layout$annotations[[149]] <- list(xref = "paper", yref = "paper", x = 0, y = 0.9, showarrow = F, xanxhor = "left", yanchor = "top", align = "left", text = "Emissions from burning of solid, liquid and

gas fuels and the manufacture of cement.", font = list(size = 18, color = "#808080")) p$layout$annotations[[150]] <- list(xref = "paper", yref = "paper", x = 0.15, y = 0.5, showarrow = F, xanxhor = "left", yanchor = "top", align = "left", text = "Annual CO_{2}emissionsfor 147 countries.", font = list(size = 13, color = "black")) p$data[[149]] <- list(x = rep(-7, 6), y = c(-6, -4, -2, 0, 2, 4), mode = "markers", marker = list(color = colors, size = 10)) p$data[[150]] <- list(x = rep(1, 6), y = c(-6, -4, -2, 0, 2, 4), mode = "text", text = rev(continent), marker = list(color = colors, size = 10)) p

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