R: Extended / Engineering Axis for Graphics

eaxis {sfsmisc}

R Documentation

Extended / Engineering Axis for Graphics

Description

An extended axis() function which labels more prettily, in particular for log-scale axes.

It makes use of plotmath or (LaTeX) expressions of the form k \times 10^k for labeling a log-scaled axis and when otherwise exponential formatting would be used (see pretty10exp).

Usage

eaxis(side, at = if(log) axTicks(side, axp=axp, log=log, nintLog=nintLog)
                 else    axTicks(side, axp=axp, log=log),
      labels = NULL, log = NULL,
      use.expr = log || format.info(as.numeric(at), digits=7)[3] > 0,
      f.smalltcl = 3/5, at.small = NULL, small.mult = NULL, equidist.at.tol = 0.002,
      small.args = list(),
      draw.between.ticks = TRUE, between.max = 4,
      outer.at = TRUE, drop.1 = TRUE, sub10 = FALSE, las = 1,
      nintLog = max(12, par("lab")[2 - is.x]),
      axp = NULL, n.axp = NULL, max.at = Inf,
      lab.type = "plotmath", lab.sep = "cdot",
      ...)

Arguments

`side`	integer in 1:4, specifying side of `axis`.
`at`	numeric vector of (“normalsized”) tick locations; by default `axTicks(side, ..)`, i.e., the same as `axis()` would use.
`labels`	`NULL` (default), `logical`, `character` or `expression`, as in `axis()`; in addition, if `NA`, `labels = TRUE` is passed to `axis()`, i.e. `pretty10exp` is not used. Use `FALSE` to suppress any labeling.
`log`	logical or `NULL` specifying if log-scale should be used; the default depends on the current plot's axis.
`use.expr`	logical specifying if `pretty10exp(.)` should be used for constructing `labels` when they are `NULL`. The default is typically good enough, but you may occasionally force `use.expr = TRUE`.
`f.smalltcl`	factor specifying the lengths of the small ticks in proportion to the normalsized, labeled ticks.
`at.small`	locations of small ticks; the default, `NULL`, uses `small.mult` and constructs “smart” locations.
`small.mult`	positive integer (or `NULL`), used when `at.small` is NULL to indicate which multiples of `at` (typically `axTicks()`) should be used as “small ticks”. The default `NULL` will use `9` in the log case and a number in 2:5 otherwise.
`equidist.at.tol`	a small positive number, a tolerance to be used for checking equidistant `at` values. Used to be hardwired at `.001` which was seen to be too small; increase it when necessary.
`small.args`	optional `list` of further arguments to the (second) `axis()` call which draws the small ticks.
`draw.between.ticks`	(only if `log` is true): logical indicating that possible (non-small) ticks between the labeled (via `at`) ones should be drawn as well (and possibly also used for `at.small` construction), see also `between.max`.
`between.max`	(only if `log` and `draw.between.ticks` are true): integer indicating ticks should be drawn (approximately) between the labeled ones.
`outer.at`	logical specifying that `at.small` should also be constructed outside the `at` range, but still inside the corresponding `par("usr")`.
`drop.1`	logical specifying if `1 \times` should be dropped from labels, passed to `pretty10exp()`.
`sub10`	logical, integer (of length 1 or 2) or `"10"`, indicating if some `10^k` should be simplified to “traditional” formats, see `pretty10exp`.
`nintLog`	only used in R > 2.13.x, when `log` is true: approximate (lower bound on) number of intervals for log scaling.
`axp`	to be passed to `axTicks()` if `at` is not specified.
`n.axp`	to be set to `axp[3]` when `axp` and `at` are not specified, in order to tweak the number of (non-small) tick marks produced from `axTicks(..)`, notably when `log` is true, set `n.axp` to 1, 2, or 3: 1: will produce tick marks at `10^j` for integer `j`, 2: gives marks `k 10^j` with `k \in \{1, 5\}`, 3: gives marks `k 10^j` with `k \in \{1, 2, 5\}` see `'xaxp'` on the `par` help page.
`max.at`	maximal number of `at` values to be used effectively. If you don't specify `at` yourself carefully, it is recommended to set this to something like `25`, but this is not the default, for back compatibility reasons.
`las`, `...`	arguments passed to (the first) `axis` call. Note that the default `las = 1` differs from `axis`'s default `las = 0`.
`lab.type`	string, passed to `pretty10exp` to choose between default `plotmath` or LaTeX label format.
`lab.sep`	separator between mantissa and exponent for LaTeX labels, see `pretty10exp`.

Author(s)

Martin Maechler

Examples

x <- lseq(1e-10, 0.1, length = 201)
plot(x, pt(x, df=3), type = "l", xaxt = "n", log = "x")
eaxis(1)
## without small ticks:
eaxis(3, at.small=FALSE, col="blue")

## If you like the ticks, but prefer traditional (non-"plotmath") labels:
plot(x,  gamma(x),   type = "l", log = "x")
eaxis(1, labels=NA)

x <- lseq(.001, 0.1, length = 1000)
plot(x, sin(1/x)*x, type = "l", xaxt = "n", log = "x")
eaxis(1)
eaxis(3, n.axp = 1)# -> xaxp[3] = 1:  only  10^j (main) ticks

## non- log-scale : draw small ticks, but no "10^k" if not needed:
x <- seq(-100, 100, length = 1000)
plot(x, sin(x)/x, type = "l", xaxt = "n")
eaxis(1)           # default -> {1, 2, 5} * 10^j  ticks
eaxis(3, n.axp = 2)# -> xaxp[3] := 2 -- approximately two (main) ticks

x <- seq(-1, 1, length = 1000)
plot(x, sin(x)/x, type = "l", xaxt = "n")
eaxis(1, small.args = list(col="blue"))

x <- x/1000
plot(x, 1-sin(x)/x, type = "l", xaxt = "n", yaxt = "n")
eaxis(1)
eaxis(2)
## more labels than default:
op <- par(lab=c(10,5,7))
plot(x, sin(x)/x, type = "l", xaxt = "n")
eaxis(1) # maybe (depending on your canvas), there are too many,
## in that case, maybe use
plot(x, sin(x)/x, type = "l", xaxt = "n")
eaxis(1, axTicks(1)[c(TRUE,FALSE)]) # drop every 2nd label
eaxis(3, labels=FALSE)

## ore use 'max.at' which thins as well:
plot(x, sin(x)/x, type = "l", xaxt = "n")
eaxis(1, max.at=6)
par(op)

### Answering R-help "How do I show real values on a log10 histogram", 26 Mar 2013
## the data:
       set.seed(1); summary(x <- rlnorm(100, m = 2, sdl = 3))
## the plot (w/o  x-axis) :
       r <- hist(log10(x), xaxt = "n", xlab = "x [log scale]")
## the nice axis:
       axt <- axTicks(1)
       eaxis(1, at = axt, labels = pretty10exp(10^axt, drop.1=TRUE))
## Additionally demo'ing   'sub10' options:
       plot(r, xaxt="n")
       eaxis(1, at = axt, labels = pretty10exp(10^axt, drop.1=TRUE, sub10 = 2))
## or
       plot(r, xaxt="n")
       eaxis(1, at = axt, labels = pretty10exp(10^axt, drop.1=TRUE, sub10 = "10"))
## or
       plot(r, xaxt="n")
       eaxis(1, at = axt, labels = pretty10exp(10^axt, drop.1=TRUE, sub10 = c(-2, 2)))