Convert matrix of PSDs to matrix of Probability Density Functions
This function converts a noiseMatrix returned by either psdList2NoiseMatrix or psdDF2NoiseMatrix
into a matrix of Probability Density values as defined by McNamara and Boaz 2005.
noiseMatrix2PdfMatrix(noiseMatrix, lo, hi, binSize)
noiseMatrix |
a |
lo |
lowest frequency bin (power level in dB) for the PDF y-axis (default=-200) |
hi |
highest frequency bin (power level in dB) for the PDF y-axis (default=-50) |
binSize |
size in dB of each bin (default=1) |
The McNamara and Boaz paper describes creating histograms of the discretized power levels at each frequency bin associated with a set of PSDs. The value in each cell of the PDF matrix is the fraction of the corrected PSDs that have that power level at that frequency bin.
To return a PDF matrix that matches those in the McNamara paper, use the default settings.
A matrix is returned with one row for each power level (-250:-50 dB) and one column for each frequency bin.
Jonathan Callahan jonathan@mazamascience.com
Seismic Noise Analysis System Using Power Spectral Density Probability Density Functions (McNamara and Boaz 2005)
## Not run:
# Create a new IrisClient
iris <- new("IrisClient", debug=TRUE)
# Get seismic data
starttime <- as.POSIXct("2011-05-05", tz="GMT") # 2011.125
endtime <- starttime + 1*24*3600
st <- getDataselect(iris,"IU","GRFO","--","BHE",starttime,endtime)
# Generate power spectral density for each hour long segment
psdList <- psdList(st)
# Convert into corrected "noiseMatrix"
noiseMatrix <- psdList2NoiseMatrix(psdList)
# Convert into McNamara "pdfMatrix"
pdfMatrix <- noiseMatrix2PdfMatrix(noiseMatrix)
# NOTE: Data need to be flipped and tranposed for the XY axes in the
# NOTE: image() function to match rows and columns in our pdfMatrix
# Plot pdfMatrix
image(t(pdfMatrix[,ncol(pdfMatrix):1]),
col=c('gray90',rainbow(9)),
axes=FALSE)
## End(Not run)Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.