Description Usage Arguments Details Value See Also Examples
Estimate the average backscattering cross section, <sigma_bs>, as the mean of the backscattering cross section, sigma_bs, weighted by the number of targets in each target strength bin.
1 | sigmaAvg(TSdf, TSrange, columnPattern = "X[[:punct:]]", prefixLen = 2)
|
TSdf |
A data frame with some of the columns containing information on the number of targets detected, named according to the target strength bin, in dB. |
TSrange |
A numeric vector of length 2, the range in dB by which to constrain the target strengths used in the estimation of the average backscattering cross section. |
columnPattern |
A character scalar containing a regular expression to be matched to the
names of |
prefixLen |
An integer scalar giving the number of characters in the prefix of the
column names identified by |
The numeric portion of the column names of TSdf
identified by
columnPattern
, represent a bin of target strengths (TS) in dB.
These TS values are converted to backscattering cross section, sigma_bs
in m^2, using TS2sigma
. The average backscattering cross
section, <sigma_bs> in m^2, is then calculated as the mean of all the
sigma_bs within the range of TSrange
, weighted by the number of
targets in each bin.
The numeric part of the column names are assumed to represent negative values in the dB scale, e.g., x.90 represents -90 dB.
A numeric vector of the average backscattering cross section, <sigma_bs>,
one for each row in TSdf
.
1 2 | mydf <- data.frame(a=letters[1:4], x.80=0:3, x.90=1:4, x.100=c(0, 1, 0, 1))
sigmaAvg(TSdf=mydf, TSrange=c(-105, -85))
|
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