问题
Magicaxis lets you unlog an axis:
library(magicaxis)
plot(1:10, 1:10, axes=FALSE)
magaxis(unlog='x')
But this assumes a base 10 logarithm. How can you specify a different base?
回答1:
author of magicaxis here. The new pre-CRAN version on my GitHub (asgr/magicaxis) has the new feature of specifying the log base. You can install this straight from GitHub using devtools. The argument is called powbase and defaults to 10. Let me know how this works for you.
Aaron
回答2:
The only part of the code the calls a log or and "un-log" seems to be hard coded to use 10^ or the function log10(). So there seems to be no way to tell the function to use a different base.
function (side = 1:2, majorn = 5, minorn = 5, tcl = 0.5, ratio = 0.5,
labels = TRUE, unlog = "Auto", mgp = c(2, 0.5, 0), mtline = 2,
xlab = NULL, ylab = NULL, crunch = TRUE, logpretty = TRUE,
prettybase = 10, hersh = FALSE, family = "sans", frame.plot = FALSE,
usepar = FALSE, ...)
{
majornlist = majorn
minornlist = minorn
unloglist = unlog
labelslist = labels
crunchlist = crunch
logprettylist = logpretty
prettybaselist = prettybase
if (length(majorn) == 1 & length(side) > 1) {
majornlist = rep(majorn, length(side))
}
if (length(minorn) == 1 & length(side) > 1) {
minornlist = rep(minorn, length(side))
}
if (length(unlog) == 1 & length(side) > 1 & (unlog[1] ==
T | unlog[1] == F | unlog[1] == "Auto")) {
unloglist = rep(unlog, length(side))
}
if (length(labels) == 1 & length(side) > 1) {
labelslist = rep(labels, length(side))
}
if (length(crunch) == 1 & length(side) > 1) {
crunchlist = rep(crunch, length(side))
}
if (length(logpretty) == 1 & length(side) > 1) {
logprettylist = rep(logpretty, length(side))
}
if (length(prettybase) == 1 & length(side) > 1) {
prettybaselist = rep(prettybase, length(side))
}
if (unlog[1] == "x") {
unloglist = rep(FALSE, length(side))
unloglist[side %in% c(1, 3)] = TRUE
}
if (unlog[1] == "y") {
unloglist = rep(FALSE, length(side))
unloglist[side %in% c(2, 4)] = TRUE
}
if (unlog[1] == "xy" | unlog[1] == "yx") {
unloglist = rep(TRUE, length(side))
}
if (length(majornlist) != length(side)) {
stop("Length of majorn vector mismatches number of axes!")
}
if (length(minornlist) != length(side)) {
stop("Length of minorn vector mismatches number of axes!")
}
if (length(unloglist) != length(side)) {
stop("Length of unlog vector mismatches number of axes!")
}
if (length(labelslist) != length(side)) {
stop("Length of labels vector mismatches number of axes!")
}
if (length(crunchlist) != length(side)) {
stop("Length of crunch vector mismatches number of axes!")
}
if (length(logprettylist) != length(side)) {
stop("Length of logpretty vector mismatches number of axes!")
}
if (length(prettybaselist) != length(side)) {
stop("Length of prettybase vector mismatches number of axes!")
}
currentfamily = par("family")
if (hersh & family == "serif") {
par(family = "HersheySerif")
}
if (hersh & family == "sans") {
par(family = "HersheySans")
}
if (hersh == F & family == "serif") {
par(family = "serif")
}
if (hersh == F & family == "sans") {
par(family = "sans")
}
if (usepar) {
tcl = par()$tcl
mgp = par()$mgp
}
for (i in 1:length(side)) {
currentside = side[i]
majorn = majornlist[i]
minorn = minornlist[i]
unlog = unloglist[i]
labels = labelslist[i]
crunch = crunchlist[i]
logpretty = logprettylist[i]
prettybase = prettybaselist[i]
lims = par("usr")
if (currentside %in% c(1, 3)) {
lims = lims[1:2]
if (par("xlog")) {
logged = T
}
else {
logged = F
}
}
else {
lims = lims[3:4]
if (par("ylog")) {
logged = T
}
else {
logged = F
}
}
lims = sort(lims)
if (unlog == "Auto") {
if (logged) {
unlog = T
}
else {
unlog = F
}
}
if (logged | unlog) {
usemultloc = (10^lims[2])/(10^lims[1]) < 50
}
else {
usemultloc = F
}
if (unlog) {
sci.tick = maglab(10^lims, n = majorn, log = T,
exptext = T, crunch = crunch, logpretty = logpretty,
usemultloc = usemultloc, prettybase = prettybase,
hersh = hersh)
major.ticks = log10(sci.tick$tickat)
uselabels = sci.tick$exp
labloc = log10(sci.tick$labat)
if (usemultloc == F) {
minors = log10(pretty(10^major.ticks[1:2], minorn +
2)) - major.ticks[1]
}
}
if (logged & unlog == F) {
sci.tick = maglab(10^lims, n = majorn, log = T,
exptext = F, crunch = crunch, logpretty = logpretty,
usemultloc = usemultloc, prettybase = prettybase,
hersh = hersh)
major.ticks = log10(sci.tick$tickat)
uselabels = sci.tick$exp
labloc = log10(sci.tick$labat)
if (usemultloc == F) {
minors = log10(pretty(10^major.ticks[1:2], minorn +
2)) - major.ticks[1]
}
}
if (logged == F & unlog == F) {
sci.tick = maglab(lims, n = majorn, log = F, exptext = F,
prettybase = prettybase, hersh = hersh)
major.ticks = sci.tick$tickat
uselabels = sci.tick$exp
labloc = sci.tick$labat
minors = pretty(major.ticks[1:2], minorn + 2) -
major.ticks[1]
}
if (logged) {
axis(side = currentside, at = 10^major.ticks, tcl = tcl,
labels = FALSE, mgp = mgp, ...)
}
else axis(side = currentside, at = major.ticks, tcl = tcl,
labels = FALSE, mgp = mgp, ...)
if (labels) {
if (logged) {
axis(side = currentside, at = 10^labloc, tick = F,
labels = uselabels, mgp = mgp, ...)
}
else axis(side = currentside, at = labloc, tick = F,
labels = uselabels, mgp = mgp, ...)
}
if (usemultloc == F) {
minors = minors[-c(1, length(minors))]
minor.ticks = c(outer(minors, major.ticks, `+`))
if (logged) {
axis(currentside, at = 10^minor.ticks, tcl = tcl *
ratio, labels = FALSE, ...)
}
else axis(currentside, at = minor.ticks, tcl = tcl *
ratio, labels = FALSE, ...)
}
if (is.null(xlab) == F & currentside == 1) {
mtext(xlab, 1, line = mtline)
}
if (is.null(ylab) == F & currentside == 2) {
mtext(ylab, 2, line = mtline)
}
}
if (frame.plot) {
box()
}
par(family = currentfamily)
}
You could try modifying the code to use a parameter for the base and log instead of log10() but this can get messy especially if the parts of magicaxis call each other.
Without magicaxis:
x <- 1:10
y <- 1:10
base <- 2
plot(x,y,axes=FALSE)
axis(1,at=x,labels = base^(x))
axis(2,at=y)
来源：https://stackoverflow.com/questions/34796231/how-make-the-x-axis-a-base-2-logarithm-in-r-with-magicaxis