corspec {seewave} | R Documentation |
This function tests the similarity between two frequency spectra by returning their maximal correlation and the frequency shift related to it.
corspec(spec1, spec2, f = NULL, plot = TRUE, plotval = TRUE, method = "spearman", col = "black", colval = "red", cexval = 1, fontval = 1, xlab = "Frequency (kHz)", ylab = "Coefficient of correlation (r)", type="l",...)
spec1 |
a first data set resulting of a spectral analysis obtained
with spec or meanspec (not in dB). This
can be either a two-column matrix (col1 = frequency, col2 = amplitude)
or a vector (amplitude). |
spec2 |
a first data set resulting of a spectral analysis obtained
with spec or meanspec (not in dB). This
can be either a two-column matrix (col1 = frequency, col2 = amplitude)
or a vector (amplitude). |
f |
sampling frequency of waves used to obtain spec1
and spec2 (in Hz). Not necessary if spec1 and/or spec2
is a two columns matrix obtained with spec or meanspec . |
plot |
logical, if TRUE plots r values against frequency shift (by default TRUE ). |
plotval |
logical, if TRUE adds to the plot maximum r value
and frequency offset (by default TRUE ). |
method |
a character string indicating which correlation coefficient is
to be computed ("pearson", "spearman", or "kendall")
(see cor ). |
col |
colour of r values. |
colval |
colour of r max and frequency offset values. |
cexval |
character size of r max and frequency offset values. |
fontval |
font of r max and frequency offset values. |
xlab |
title of the frequency axis. |
ylab |
title of the r axis. |
type |
if plot is TRUE , type of plot that should be drawn.
See plot for details (by default "l" for lines). |
... |
other plot graphical parameters. |
It is important not to have data in dB.
Successive correlations between spec1
and spec2
are computed when regularly
shifting spec2
towards lower or higher frequencies.
The maximal correlation is obtained at a particular shift (frequency offset).
This shift may be positive or negative.
The corresponding p value, obtained with cor.test
, is plotted.
Inverting spec1
and spec2
may give slight different results, see examples.
If plot
is FALSE
, corspec
returns a list containing four
components:
r |
a two-column matrix, the first colum corresponding to the frequency
shift (frequency x-axis) and the second column corresponding to the successive
r correlation values between spec1 and spec2 (correlation y-axis). |
rmax |
the maximum correlation value between spec1 and spec2 . |
p |
the p value corresponding to rmax . |
f |
the frequency offset corresponding to rmax . |
Jerome Sueur sueur@mnhn.fr
Hopp, S. L., Owren, M. J. and Evans, C. S. (Eds) 1998. Animal acoustic communication. Springer, Berlin, Heidelberg.
spec
, meanspec
, corspec
,
covspectro
, cor
, cor.test
.
data(tico) # compare the two first notes spectra a<-spec(tico,f=22050,wl=512,at=0.2,plot=FALSE) c<-spec(tico,f=22050,wl=512,at=1.1,plot=FALSE) op<-par(mfrow=c(2,1), mar=c(4.5,4,3,1)) spec(tico,f=22050,at=0.2,col="blue") par(new=TRUE) spec(tico,f=22050,at=1.1,col="green") legend(x=8,y=0.5,c("Note A", "Note C"),lty=1,col=c("blue","green"),bty="o") par(mar=c(5,4,2,1)) corspec(a,c, ylim=c(-0.25,0.8),xaxs="i",yaxs="i",las=1) par(op) # different correlation methods give different results... op<-par(mfrow=c(3,1)) corspec(a,c,xaxs="i",las=1, ylim=c(-0.25,0.8)) title("spearmann correlation (by default)") corspec(a,c,xaxs="i",las=1,ylim=c(0,1),method="pearson") title("pearson correlation") corspec(a,c,xaxs="i",las=1,ylim=c(-0.23,0.5),method="kendall") title("kendall correlation") par(op) # inverting x and y does not give exactly similar results op<-par(mfrow=c(2,1),mar=c(2,4,3,1)) corspec(a,c) corspec(c,a) par(op)