Write text to plot with halo underneath

Description

Write text to plot. A field the size of each label is drawn beneath it, so the text can be read easily even if there are many points in the plot. Fields can be rectangular, elliptic or rectangular with roundeed edges.

Usage

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textField(x, y, labels = seq_along(x), fill = "white", border = NA,
  expression = NA, margin = 0.3, field = "rounded", nv = 1000,
  rounding = 0.75, lty = par("lty"), lwd = par("lwd"), cex = par("cex"),
  xpd = par("xpd"), adj = par("adj"), pos = NULL, offset = 0.5,
  quiet = TRUE, ...)

Arguments

x

X coordinates, if necessary, they are recycled

y

Y coordinates

labels

labels to be placed at the coordinates, as in text. DEFAULT: seq_along(x)

fill

fill is recycled if necessary. With a message when quiet = FALSE. DEFAULT: "white"

border

ditto for border. DEFAULT: NA

expression

If TRUE, labels are converted to expression for better field positioning through expression bounding boxes. If NA, it is set to TRUE for labels without line breaks (Newlines, "\n"). If FALSE, no conversion happens. DEFAULT: NA

margin

added field space around words (multiple of em/ex). DEFAULT: 0.3

field

'rectangle', 'ellipse', or 'rounded', partial matching is performed. DEFAULT: "rounded"

nv

number of vertices for field = "ellipse" or "rounded". low: fast drawing. high: high resolution in vector graphics as pdf possible. DEFAULT: 1000

rounding

between 0 and 1: portion of height that is cut off rounded at edges when field = "rounded". DEFAULT: 0.75

lty

line type. DEFAULT: par("lty")

lwd

line width. DEFAULT: par("lwd")

cex

character expansion. DEFAULT: par("cex")

xpd

expand text outside of plot region ("figure")?. DEFAULT: par("xpd")

adj

vector of length one or two. DEFAULT: par("adj")

pos

in 'text', pos overrides adj values. DEFAULT: NULL

offset

I want the field to still be drawn with adj, but have it based on pos. DEFAULT: 0.5

quiet

Suppress warning when Arguments are recycled? DEFAULT: TRUE

...

further arguments passed to strwidth and text, like font, vfont, family

Details

Specifying pos and offset will currently change the position of the text, but not of the field.
srt is not supported yet.
lend, ljoin and lmitre can not be specified for rect, to keep argument number low.
density (crosshatch etc.) is not supported, as this would distract from the text. # Search Engine Keywords: R Text visible on top R labeling with color underneath R Creating text with a halo R Text with shadow

Value

None

Author(s)

Berry Boessenkool, berry-b@gmx.de, April 2013 + March 2014

References

with inspiration taken from ordilabel in package vegan and thanks to Jari Oksanen for his comments

See Also

text; shadowtext in package TeachingDemos, see http://stackoverflow.com/questions/25631216; s.label in package ade4, which is not so versatile and doesn't work with logarithmic axes

Examples

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# TextFields with mixed field shapes ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
set.seed(13);  plot(cumsum(rnorm(100)), type="l", main="berryFunctions::textField")
for(i in 2:7) lines(cumsum(rnorm(100)), col=i)
textField(40, 4, "default")
textField(40, 0, "some options", col=2, fill=4, margin=c(-0.4, 0.9), font=2)
# Ellipsis (looks better in vector graphics like pdf):
textField(80, 2, "field='ellipse'", field="ell", mar=c(0.5, 2.3), border=5)
# Rectangular field with edges rounded:
textField(60,-3, "field='Rounded'", field="rounded", fill="orange", cex=1.7)

# Field type can be abbreviated (partial matching), margin may need adjustment:
textField(90, 5, "short", field="ell", fill=7, border=4, mar=-0.4)

# Rounded can also vectorized:
textField(30, c(2,0,-2,-4,-6), paste("rounding =",seq(0,1,len=5)), field="round",
    fill=(2:6), mar=1, rounding=seq(0,1,len=5), border=1)
# turn off warning about recycling:
textField(80, c(-5,-6.5), c("Ja", "Nein"), field="round", fill=6:8, quiet=TRUE)


set.seed(007); plot(rnorm(1e4)) ; abline(v=0:5*2e3, col=8)
# Default settings:
textField(5000, 0, "Here's some good text")
# right-adjusted text (the field box still extends 'margin' stringwidths em):
textField(2000, -1, "Some more (smores!)", cex=1.5, adj=0, col=2)
# Field color, no extra margin beyond baseline (excluding descenders):
textField(2000, -2, "more yet", col=2, fill="blue", margin=0)
# margin can be one number for both x and y direction ... :
textField(1000, 2, "Up we go", fill=7, margin=1.4)
# ... or two (x and y different), even negative:
textField(5000, 2, "to the right", col=2, fill=4, margin=c(-0.4, 0.9))
# Fonts can be set as well:
textField(5000, 1, "And boldly down in bold font", font=2, border=3)
# Text can expand outsinde of the plot region (figure) into the margins:
textField(11000, -2, "Hi, I'm a long block of text", adj=1, fill="red")
textField(11000, -3, "You're not outside the plot!", adj=1, xpd=TRUE, fill="red")
# And most parameters can be vectorized, while x/y are recycled:
textField(3000, c(-3, -3.7), c("0", "good"), border=c("red",3), lty=1:2)


# textField even works on logarithmic axes:
mylabel <- c("This","is (g)","the","ever-\n great","Sparta")
plot(10^runif(5000, -1,2), log="y", col=8)
textField(1000, c(100,20,4,2,0.5), mylabel, fill=2, mar=0, expression=FALSE)
textField(2500, c(100,20,4,2,0.5), mylabel, fill=4, mar=0, expression=TRUE)
textField(4000, c(100,20,4,2,0.5), mylabel, fill=3, mar=0)
textField(c(1,2.5,4)*1000, 0.2, paste("expression=\n", c("FALSE","TRUE","NA")))

# In most devices, vertical adjustment is slightly off when the character string
# contains no descenders. The default is for centered text:  adj = c(0.5, NA).
# For drawing the field, adj[2] is in this case set to 0.5.
# Text positioning is different for NA than for 0.5, see details of ?text
# I'm working on it through expression, which does not work with newlines yet

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