# plotFun: Plotting mathematical expressions In ProjectMOSAIC/mosaic: Project MOSAIC Statistics and Mathematics Teaching Utilities

## Description

Plots mathematical expressions in one and two variables.

## Usage

 ``` 1 2 3 4 5 6 7 8 9 10``` ```plotFun(object, ..., plot = trellis.last.object(), add = NULL, under = FALSE, xlim = NULL, ylim = NULL, npts = NULL, ylab = NULL, xlab = NULL, zlab = NULL, filled = TRUE, levels = NULL, nlevels = 10, labels = TRUE, surface = FALSE, groups = NULL, col = trellis.par.get("superpose.line")\$col, col.regions = topo.colors, type = "l", lwd = trellis.par.get("superpose.line")\$lwd, lty = trellis.par.get("superpose.line")\$lty, alpha = NULL, discontinuities = NULL, discontinuity = 1, interactive = rstudio_is_available()) ```

## Arguments

 `object` a mathematical expression or a function "of one variable" which will converted to something intuitively equivalent to `object(x) ~ x`. (See examples) `...` additional parameters, typically processed by `lattice` functions such as `lattice::xyplot()`, `lattice::levelplot()` or their panel functions. Frequently used parameters include `main`main title for plot `sub`subtitle for plot `lwd`line width `lty`line type `col`a color or a (small) integer indicating which color in the current color scheme is desired. Additionally, these arguments can be used to specify parameters for the function being plotted and to specify the plotting window with natural names. See the examples for such usage. `plot` a trellis object; by default, the most recently created trellis plot. When `add` is `TRUE`, the new function will be plotted into a layer added to this object. `add` if `TRUE`, then add a layer to an existing plot rather than creating a new plot. If `NULL`, this will be determined by the value of `under`. `under` if `TRUE`, then new layer is added beneath existing layers `xlim` limits for x axis (or use variable names, see examples) `ylim` limits for y axis (or use variable names, see examples) `npts` number of points for plotting. `ylab` label for y axis `xlab` label for x axis `zlab` label for z axis (when in surface-plot mode) `filled` fill with color between the contours (`TRUE` by default) `levels` levels at which to draw contours `nlevels` number of contours to draw (if `levels` not specified) `labels` if `FALSE`, don't label contours `surface` draw a surface plot rather than a contour plot `groups` grouping argument ala lattice graphics `col` vector of colors for line graphs and contours `col.regions` a vector of colors or a function (`topo.colors` by default) for generating such `type` type of plot (`"l"` by default) `lwd` vector of line widths for line graphs `lty` vector of line types for line graphs `alpha` number from 0 (transparent) to 1 (opaque) for the fill colors `discontinuities` a vector of input values at which a function is discontinuous or `NULL` to use a heuristic to auto-detect. `discontinuity` a positive number determining how sensitive the plot is to potential discontinuity. Larger values result in less sensitivity. The default is 1. Use `discontinuity = Inf` to disable discontinuity detection. Discontinuity detection uses a crude numerical heuristic and may not give the desired results in all cases. `interactive` a logical indicating whether the surface plot should be interactive.

## Details

makes plots of mathematical expressions using the formula syntax. Will draw both line plots and contour/surface plots (for functions of two variables). In RStudio, the surface plot comes with sliders to set orientation. If the colors in filled surface plots are too blocky, increase `npts` beyond the default of 50, though `npts=300` is as much as you're likely to ever need. See examples for overplotting a constraint function on an objective function.

## Value

a `trellis` object

## Examples

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35``` ```plotFun( a*sin(x^2)~x, xlim=range(-5,5), a=2 ) # setting parameter value plotFun( u^2 ~ u, ulim=c(-4,4) ) # limits in terms of u # Note roles of ylim and y.lim in this example plotFun( y^2 ~ y, ylim=c(-2,20), y.lim=c(-4,4) ) # Combining plot elements to show the solution to an inequality plotFun( x^2 -3 ~ x, xlim=c(-4,4), grid=TRUE ) ladd( panel.abline(h=0,v=0,col='gray50') ) plotFun( (x^2 -3) * (x^2 > 3) ~ x, type='h', alpha=.1, lwd=4, col='lightblue', add=TRUE ) plotFun( sin(x) ~ x, groups=cut(x, findZeros(sin(x) ~ x, within=10)\$x), col=c('blue','green'), lty=2, lwd=3, xlim=c(-10,10) ) plotFun( sin(x) ~ x, groups=cut(x, findZeros(sin(x) ~ x, within=10)\$x), col=c(1,2), lty=2, lwd=3, xlim=c(-10,10) ) ## plotFun( sin(2*pi*x/P)*exp(-k*t)~x+t, k=2, P=.3) f <- rfun( ~ u & v ) plotFun( f(u=u,v=v) ~ u & v, u.lim=range(-3,3), v.lim=range(-3,3) ) plotFun( u^2 + v < 3 ~ u & v, add=TRUE, npts=200 ) if (require(mosaicData)) { # display a linear model using a formula interface model <- lm(wage ~ poly(exper,degree=2), data=CPS85) fit <- makeFun(model) xyplot(wage ~ exper, data=CPS85) plotFun(fit(exper) ~ exper, add=TRUE, lwd=3, col="red") # Can also just give fit since it is a "function of one variable" plotFun(fit, add=TRUE, lwd=2, col='white') } # Attempts to find sensible axis limits by default plotFun( sin(k*x)~x, k=0.01 ) # Plotting a linear model with multiple predictors. mod <- lm(length ~ width * sex, data=KidsFeet) fitted.length <- makeFun(mod) xyplot(length ~ width, groups=sex, data=KidsFeet, auto.key=TRUE) plotFun(fitted.length(width, sex="B") ~ width, add=TRUE, col=1) plotFun(fitted.length(width, sex="G") ~ width, add=TRUE, col=2) ```

ProjectMOSAIC/mosaic documentation built on Aug. 19, 2018, 9:14 a.m.