monthAxis: Label date axis

Description

Labels date axes at sensible monthly intervals in the time domain of years to decades.

Usage

monthAxis(side = 1, time = NA, origin = "1970-01-01",
  mlabels = substr(month.abb, 1, 1), yformat = "%Y", nmonths = 3,
  nym_half = 3.5, nym_none = 5, mcex = 0.7, ycex = 1,
  mtcl = par("tcl"), ytcl = par("tcl") - 1.7, mline = -1, yline = 0.2,
  las = 1, lrange = NA, ym = TRUE, mgp = c(3, 1, 0), mt = NULL,
  ml = NULL, yt = NULL, yl = NULL, quiet = FALSE, ...)

Arguments

side

Which axis is to be labeled? DEFAULT: 1

time

Logical indicating whether the axis is POSIXct, not Date. DEFAULT: NA, meaning axis value >1e5

origin

Origin foras.Date and as.POSIXct. DEFAULT: "1970-01-01"

mlabels

Labels for the months. DEFAULT: J,F,M,A,M,J,J,A,S,O,N,D

yformat

Format of year labels, see details in strptime. Use yformat=" " (with space) to suppress year labeling. DEFAULT: "%Y"

nmonths

Minimum number of months required before a year at the axis boundary is labeled. DEFAULT: 3

nym_half

Number of years on axis above which only every second month is labeled. DEFAULT: 3.5

nym_none

Number of years on axis above which the months are not labeled. DEFAULT: 5

mcex

cex.axis (letter size) for month labels. DEFAULT: 0.7

ycex

cex.axis (letter size) for year labels. DEFAULT: 1

mtcl

Month tick length (negative text line height units). 0 to suppress ticks. DEFAULT: par("tcl") = -0.5

ytcl

Year tick length (negative text line height units). 0 to suppress ticks. DEFAULT: par("tcl")-1.7 = -2.2

mline

Line of month labels. DEFAULT: -1

yline

Line of year labels. DEFAULT: 0.2

las

LabelAxisStyle for orientation of labels. DEFAULT: 1 (upright)

lrange

Label range (two Date values). DEFAULT: NA = internally computed from par("usr")

Kept for back reference. DEFAULT: TRUE

mgp

MarGin Placement. Suggested not to change this, since _tcl and _line defaults are chosen for the DEFAULT: c(3,1,0)

mt, ml, yt, yl

Lists with further arguments passed to axis, like lwd, col.ticks, lwd.ticks, hadj, lty, separately for month ticks, month labels, year ticks, year labels. DEFAULT: NULL

quiet

Suppress warning about short time axis? DEFAULT: FALSE

…

Arguments passed to axis for all 4 elements.

Value

List with locations of month and year labels and ticks, each a Date vector.

Examples

Run this code

# NOT RUN {
set.seed(007) # for reproducibility
timePlot <- function(nydays, start="2013-08-25", ...)
   plot(as.Date(start)+sort(c(0,sample(1:nydays, 50))),
        cumsum(rnorm(51)), type="l", xaxt="n", ann=FALSE, las=1, ...)

timePlot(1100)
monthAxis()
monthAxis(1, nmonths=6, col.axis="red") # 2013 not labeled anymore
monthAxis(side=3, nym_half=2) # if axis > 2 years, label only partially

timePlot(2e3)
monthAxis()   # long time series (>nym_none) only have years labeled
monthAxis(side=3, font=2)

timePlot(900)
monthAxis(side=3, mtcl=0) # no tick lines between months
monthAxis(ycex=1.4, ytcl=2, lwd.ticks=2)
monthAxis(yline=1, col.axis=4, col=4)
monthAxis(mcex=1, col.axis="red", yformat=" ") # no years labeled

timePlot(800)
monthAxis()
monthAxis(mgp=c(2,1,0)) # the same. element 2 is relevant here
monthAxis(mgp=c(3,0,0)) # requires change in mline andy yline placement

timePlot(400)
ma <- monthAxis(lwd=3, yl=list(col.axis=3), mlabels=letters[1:12], mcex=1)
abline(v=ma$mtics, col=8) # use output from monthAxis for other functions

timePlot(80)
monthAxis(mlabels=month.abb, mcex=1) # short time series give a warning

timePlot(80, "2013-11-14")
monthAxis(mlabels=month.abb, mcex=1, nmonths=0, quiet=TRUE)

# Time axis instead of date axis:
plot(as.POSIXct(Sys.time()+c(0,2)*360*24*3600), 1:2, xaxt="n")
monthAxis(nmonths=2)

timePlot(800, "2015-01-01")
monthAxis()
timePlot(900, "2015-01-01", xaxs="i")
monthAxis()
timePlot(300, "2015-01-01", xaxs="i")
monthAxis() # if less than a full year is covered, the year label is centered

# }

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