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r4d

Use R to draw a 4d figure

I have some data in CSV file and want to draw a 4d graphic. The x, y, z axis is respectively one column in the file. and the 4th dimension is a color respective of the value of another column in the file. How can I get a plot with both the x,y,z and color in R?

Solution

  • You will be able to make a 3D plot with color information encoded according to another variable in the data set. It depends on whether you need a surface or a scatterplot. For example, a 3D scatterplot package (install.packages("scatterplot3d") would result, using the mtcars dataset, in

    library(scatterplot3d)
# create column indicating point color
mtcars$pcolor[mtcars$cyl==4] <- "red"
mtcars$pcolor[mtcars$cyl==6] <- "blue"
mtcars$pcolor[mtcars$cyl==8] <- "darkgreen"
with(mtcars, {
    s3d <- scatterplot3d(disp, wt, mpg,        # x y and z axis
                  color=pcolor, pch=19,        # circle color indicates no. of cylinders
                  type="h", lty.hplot=2,       # lines to the horizontal plane
                  scale.y=.75,                 # scale y axis (reduce by 25%)
                  main="3-D Scatterplot Example 4",
                  xlab="Displacement (cu. in.)",
                  ylab="Weight (lb/1000)",
                  zlab="Miles/(US) Gallon")
     s3d.coords <- s3d$xyz.convert(disp, wt, mpg)
     text(s3d.coords$x, s3d.coords$y,     # x and y coordinates
          labels=row.names(mtcars),       # text to plot
          pos=4, cex=.5)                  # shrink text 50% and place to right of points)
# add the legend
legend("topleft", inset=.05,      # location and inset
    bty="n", cex=.5,              # suppress legend box, shrink text 50%
    title="Number of Cylinders",
    c("4", "6", "8"), fill=c("red", "blue", "darkgreen"))
})

    yielding

    3d scatterplot with color information

    You can find a list of examples, including the one above, here.