| pHcolourmap {spatstat.geom} | R Documentation |
Colour Map for pH Values
Description
Create a colour map for values of pH.
Usage
pHcolourmap(range = c(0, 14), ..., n=256, step = FALSE)
pHcolour(pH)
Arguments
n |
Number of different colour values to be used, when |
range |
Range of |
step |
Logical value. If |
... |
Ignored. |
pH |
Numerical value or numeric vector of values of |
Details
In chemistry the hydrogen potential pH measures how acidic or basic
a solution is.
The function pHcolour calculates the colour associated with
a given value of pH, according to a standard mapping in which
neutral pH=7 is green,
acidic values pH < 7 are yellow or red,
and basic values pH > 7 are blue.
The function pHcolour takes a numerical value or vector of
values of pH and returns a character vector containing the
corresponding colours.
The function pHcolourmap produces a colour map for numerical values
of pH, using the same consistent mapping of pH
values to colours.
The argument range specifies the range of pH values that
will be mapped by the resulting colour map. It should be a numeric
vector of length 2 giving the minimum and maximum values of pH
that the colour map will handle. (Colour maps created with different
values of range use essentially the same mapping of colours,
but when plotted as colour ribbons, display only the specified range.)
If step=FALSE (the default) the colours change
continuously with increasing values of the input. There will be
n different colour values in the colour map. Usually n
should be a large number.
If step=TRUE, the colour is constant on each unit interval of
pH values. That is, any value of pH in the interval
[k, k+1], where k is an integer, will be mapped to the
same colour.
Value
The return value of pHcolour is a character string or
a vector of character strings representing colours.
The return value of pHcolourmap
is a colour map (object of class "colourmap").
Author(s)
Adrian Baddeley Adrian.Baddeley@curtin.edu.au.
See Also
Examples
pHcolour(7)
plot(pHcolourmap())
plot(pHcolourmap(step=TRUE))
plot(pHcolourmap(c(3, 8)))