ggplot2 (version 0.9.1)

annotation_logticks: Annotation: log tick marks

Description

This annotation adds log tick marks with diminishing spacing. These tick marks probably make sense only for base 10.

Usage

annotation_logticks(base = 10, sides = "bl",
    scaled = TRUE, short = unit(0.1, "cm"),
    mid = unit(0.2, "cm"), long = unit(0.3, "cm"))

Arguments

base

the base of the log (default 10)

sides

a string that controls which sides of the plot the log ticks appear on. It can be set to a string containing any of "trbl", for top, right, bottom, and left.

short

a unit object specifying the length of the short tick marks

mid

a unit object specifying the length of the middle tick marks. In base 10, these are the "5" ticks.

long

a unit object specifying the length of the long tick marks. In base 10, these are the "1" (or "10") ticks.

scaled

is the data already log-scaled? This should be TRUE (default) when the data is already transformed with log10() or when using scale_y_log10. It should be FALSE when using coord_trans(y = "l

See Also

scale_y_continuous, scale_y_log10 for log scale transformations.

coord_trans for log coordinate transformations.

Examples

# Make a log-log plot (without log ticks)
library(MASS)
library(scales)
a <- ggplot(Animals, aes(x = body, y = brain)) + geom_point() +
     scale_x_log10(breaks = trans_breaks("log10", function(x) 10^x),
                   labels = trans_format("log10", math_format(10^.x))) +
     scale_y_log10(breaks = trans_breaks("log10", function(x) 10^x),
                   labels = trans_format("log10", math_format(10^.x))) +
     theme_bw()

a + annotation_logticks()                # Default: log ticks on bottom and left
a + annotation_logticks(sides = "lr")    # Log ticks for y, on left and right
a + annotation_logticks(sides = "trbl")  # All four sides

# Hide the minor grid lines because they don't align with the ticks
a + annotation_logticks(sides = "trbl") + opts(panel.grid.minor = theme_blank())


# Another way to get the same results as 'a' above: log-transform the data before
b <- ggplot(Animals, aes(x = log10(body), y = log10(brain))) + geom_point() +
     scale_x_continuous(name = "body", labels = math_format(10^.x)) +
     scale_y_continuous(name = "brain", labels = math_format(10^.x)) +
     theme_bw()+ opts(panel.grid.minor = theme_blank())

b + annotation_logticks()


# This shows log(x) on the axes
d <- ggplot(Animals, aes(x = log10(body), y = log10(brain))) + geom_point() +
     theme_bw()

d + annotation_logticks()


# Using a coordinate transform requires scaled = FALSE
t <- ggplot(Animals, aes(x = body, y = brain)) + geom_point() +
     coord_trans(xtrans = "log10", ytrans = "log10") + theme_bw()

t + annotation_logticks(scaled = FALSE)


# Change the length of the ticks
library(grid)
a + annotation_logticks(short = unit(.5,"mm"), mid = unit(3,"mm"), long = unit(4,"mm"))