spread.labs | R Documentation |
This function takes as set of coordinates and spreads out the close values so that they can be used in labeling plots without overlapping.
spread.labs(x, mindiff, maxiter = 1000, stepsize = 1/10, min = -Inf, max = Inf)
x |
The coordinate values (x or y, not both) to spread out. |
mindiff |
The minimum distance between return values |
maxiter |
The maximum number of iterations |
stepsize |
How far to move values in each iteration |
min |
Minimum bound for returned values |
max |
Maximum bound for returned values |
Sometimes the desired locations for labels in plots results in the
labels overlapping. This function takes the coordinate values (x or
y, not both) and finds those points that are less than mindiff
(usually a function of strheight
or strwidth
) apart and
increases the space between them (by stepsize
*
mindiff
). This may or may not be enough and moving some points
away from their nearest neighbor may move them too close to another
neighbor, so the process is iterated until either maxiter
steps
have been tried, or all the values are at least mindiff
apart.
The min
and max
arguments prevent the values from going
outside that range (they should be specified such that the original
values are all inside the range).
The values do not need to be presorted.
A vector of coordinates (order corresponding to the original x
)
that can be used as a replacement for x
in placing labels.
Greg Snow, 538280@gmail.com
text
, the spread.labels
function in the
plotrix
package.
# overlapping labels
plot(as.integer(state.region), state.x77[,1], ylab='Population',
xlab='Region',xlim=c(1,4.75), xaxt='n')
axis(1, at=1:4, lab=levels(state.region) )
text( as.integer(state.region)+.5, state.x77[,1], state.abb )
segments( as.integer(state.region)+0.025, state.x77[,1],
as.integer(state.region)+.375, state.x77[,1] )
# now lets redo the plot without overlap
tmp.y <- state.x77[,1]
for(i in levels(state.region) ) {
tmp <- state.region == i
tmp.y[ tmp ] <- spread.labs( tmp.y[ tmp ], 1.2*strheight('A'),
maxiter=1000, min=0 )
}
plot(as.integer(state.region), state.x77[,1], ylab='Population',
xlab='Region', xlim=c(1,4.75), xaxt='n')
axis(1, at=1:4, lab=levels(state.region) )
text( as.integer(state.region)+0.5, tmp.y, state.abb )
segments( as.integer(state.region)+0.025, state.x77[,1],
as.integer(state.region)+0.375, tmp.y )
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