R: Frequency Scatterplot

ggfreqScatter {Hmisc} | R Documentation

## Frequency Scatterplot

### Description

Uses `ggplot2` to plot a scatterplot or dot-like chart for the case where there is a very large number of overlapping values. This works for continuous and categorical `x` and `y`. For continuous variables it serves the same purpose as hexagonal binning. Counts for overlapping points are grouped into quantile groups and level of transparency and rainbow colors are used to provide count information.

The result can also be passed to `ggplotly`. Actual cell frequencies are added to the hover text in that case.

### Usage

    ggfreqScatter(x, y, bins=50, g=10, cuts=NULL,
                  xtrans = function(x) x,
                  ytrans = function(y) y,
                  xbreaks = pretty(x, 10),
                  ybreaks = pretty(y, 10),
                  xminor  = NULL, yminor = NULL,
                  xlab = as.character(substitute(x)),
                  ylab = as.character(substitute(y)),
                  fcolors = viridis::viridis(10), nsize=FALSE,
                  html=FALSE, prfreq=FALSE, ...)

### Arguments

`x` | x-variable
`y` | y-variable
`bins` | for continuous `x` or `y` is the number of bins to create by rounding. Ignored for categorical variables. If a 2-vector, the first element corresponds to `x` and the second to `y`.
`g` | number of quantile groups to make for frequency counts. Use `g=0` to use frequencies continuously for color and alpha coding. This is recommended only when using `plotly`.
`cuts` | instead of using `g`, specify `cuts` to provide the vector of cuts for categorizing frequencies for assignment to colors
`xtrans,ytrans` | functions specifying transformations to be made before binning and plotting
`xbreaks,ybreaks` | vectors of values to label on axis, on original scale
`xminor,yminor` | values at which to put minor tick marks, on original scale
`xlab,ylab` | axis labels. If not specified and variable has a `label`, that label will be used.
`fcolors` | `colors` argument to pass to `scale_color_gradientn` to color code frequencies
`nsize` | set to `TRUE` to not vary color or transparency but instead to size the symbols in relation to the number of points. Best with both `x` and `y` are discrete. `ggplot2` `size` is taken as the fourth root of the frequency. If there are 15 or unique frequencies all the unique frequencies are used, otherwise `g` quantile groups of frequencies are used.
`html` | set to `TRUE` to use html in axis labels instead of plotmath
`prfreq` | set to `TRUE` to print the frequency distributions of the binned coordinate frequencies
`...` | arguments to pass to `geom_point` such as `shape` and `size`

### Value

a `ggplot` object

### Author(s)

Frank Harrell

### See Also

`cut2`

### Examples

    set.seed(1)
    x <- rnorm(1000)
    y <- rnorm(1000)
    count <- sample(1:100, 1000, TRUE)
    x <- rep(x, count)
    y <- rep(y, count)
    # color=alpha=NULL below makes loess smooth over all points
    g <- ggfreqScatter(x, y) +   # might add g=0 if using plotly
          geom_smooth(aes(color=NULL, alpha=NULL), se=FALSE) +
          ggtitle("Using Deciles of Frequency Counts, 2500 Bins")
    g
    # plotly::ggplotly(g, tooltip='label')  # use plotly, hover text = freq. only
    # Plotly makes it somewhat interactive, with hover text tooltips

    # Try with x categorical
    x1 <- sample(c('cat', 'dog', 'giraffe'), length(x), TRUE)
    ggfreqScatter(x1, y)

    # Try with y categorical
    y1 <- sample(LETTERS[1:10], length(x), TRUE)
    ggfreqScatter(x, y1)

    # Both categorical, larger point symbols, box instead of circle
    ggfreqScatter(x1, y1, shape=15, size=7)
    # Vary box size instead
    ggfreqScatter(x1, y1, nsize=TRUE, shape=15)

[Package Hmisc version 4.0-3 Index]