R Scatter Plot: symbol color represents number of overlapping points

by

One option is to use densCols() to extract kernel densities at each point. Mapping those densities to the desired color ramp, and plotting points in order of increasing local density gets you a plot much like those in the linked article. 

## Data in a data.frame
x1 <- rnorm(n=1E3, sd=2)
x2 <- x1*1.2 + rnorm(n=1E3, sd=2)
df <- data.frame(x1,x2)

## Use densCols() output to get density at each point
x <- densCols(x1,x2, colramp=colorRampPalette(c("black", "white")))
df$dens <- col2rgb(x)[1,] + 1L

## Map densities to colors
cols <-  colorRampPalette(c("#000099", "#00FEFF", "#45FE4F", 
                            "#FCFF00", "#FF9400", "#FF3100"))(256)
df$col <- cols[df$dens]

## Plot it, reordering rows so that densest points are plotted on top
plot(x2~x1, data=df[order(df$dens),], pch=20, col=col, cex=2)

enter image description here

More Related Contents:

  1. Conditional coloring of cells in table
  2. heatmap-like plot, but for categorical variables
  3. How to save a plot as image on the disk?
  4. Plot two graphs in same plot in R
  5. How to set limits for axes in ggplot2 R plots?
  6. Shading a kernel density plot between two points.
  7. Force the origin to start at 0
  8. Replace X-axis with own values
  9. Plotting time-series with Date labels on x-axis
  10. How to set multiple legends / scales for the same aesthetic in ggplot2?
  11. Rotating x axis labels in R for barplot
  12. Getting LaTeX into R Plots
  13. How can I plot data with confidence intervals?
  14. Difference between passing options in aes() and outside of it in ggplot2
  15. Plot polynomial regression curve in R
  16. Use stat_summary to annotate plot with number of observations
  17. Filling area under curve based on value
  18. ggplot2: How to specify multiple fill colors for points that are connected by lines of different colors
  19. change background and text of strips associated to multiple panels in R / lattice
  20. Insert blanks into a vector for, e.g., minor tick labels in R
  21. plot.new has not been called yet
  22. how to jitter/dodge geom_segments so they remain parallel?
  23. How to fit a smooth curve to my data in R?
  24. Control the size of points in an R scatterplot?
  25. Plotting multiple time series on the same plot using ggplot()
  26. Special characters and superscripts on plot axis titles
  27. Remove unused factor levels from a ggplot bar plot
  28. Get margin line locations in log space
  29. R X-axis Date Labels using plot()
  30. Text wrap for plot titles

Leave a Comment