Description Usage Arguments Details Value References Examples
Transformations appropriate for ecological data.
1 2 3 4 5 6 7 | asin_sqrt(x, ...)
genlogtrans(x, ...)
pseudo_log(x, sigma = 1, backtransform = FALSE)
standardize(x, from = 0, to = 1, na.rm = TRUE, ...)
|
x |
vector or array of values to transform. |
... |
further arguments passed to other methods. |
sigma |
numeric, curvature scale factor for pseudo-log transform. |
backtransform |
logical, perform pseudo-log backward transformation? Default 'backtransform = FALSE' gives the forward transformation. |
from, to |
standardizes from low to high values; default is from 0 to 1. |
na.rm |
logical, should missing values (including 'NaN') be removed? |
asin_sqrt
= Arc-sine square root transform:
Appropriate for vegetation cover and other proportion data. Forces
data to 0-1 scale if any original values were outside this range.
Follows pg. 69 of McCune & Grace (2002).
genlogtrans
= Generalized log-transform:
Log transform for non-negative values, preserves original order of magnitudes
while properly handling values = 0 and << 1. Follows pg. 69 of McCune &
Grace (2002).
pseudo_log
= Pseudo-logarithmic transform:
Log-like transformation for positive and negative values. Useful for color
scales. Change sigma
to vary curvature/linearity around zero.
standardize
= Range standardize:
Standardizes data to 0-1 scale based on min/max values.
Values on the modified scale.
McCune, B., and J. B. Grace. 2002. Analysis of Ecological Communities. MjM Software, Gleneden Beach, Oregon, USA. 304 pp.
1 2 3 4 5 6 7 8 9 10 11 12 | set.seed(21)
x <- (rbeta(99, 0.5, 1) - 0.15) * 100
x1 <- asin_sqrt(x) # forces 0-1 scale
x2 <- genlogtrans(x) # only for non-negative values, negative become NaN
x3 <- pseudo_log(x) # handles positive and negative values
x4 <- standardize(x) # forces 0-1 scale
par(mfrow=c(2,2))
plot(x, x1)
plot(x, x2)
plot(x, x3)
plot(x, x4)
par(mfrow=c(1,1))
|
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