similar to: Spectral Analysis

Displaying 20 results from an estimated 200 matches similar to: "Spectral Analysis"

2002 Jul 23
2
Converting dates?
Dear R-users I have some doubts about with converting dates... e.g. dates data 23/12/1975 0.8678 03/01/1976 0.8736 28/01/1976 0.765 13/03/1976 0,9654 ... I think that converting these dates can easily my plots... is there a R function to convert these dates to a julian dates and so plot that variables?? The help files as.POSIXlt, POSIXt and others don't aswer my doubts...
2002 Aug 20
1
About lm()
Dear Mr. and Mrs. I'm very grateful for these software and this list. My question is: when a use linear multiple regression (lm()) for my data, abundance ichthyoplankton ~ salinity + temperature + month of the year(f1 is a factor: 1 for january, 2 for february, ..., 12 for december), the summary() of results is ... Coefficients: Estimate Std. Error t value Pr(>|t|)
2008 Mar 27
6
help! - spectral analysis - spec.pgram
Can someone explain me this spec.pgram effect? Code: period.6<-c(0,0,0,0,0,10,0,0,0,0,0,10,0,0,0,0,0,10,0,0,0,0,0,10,0,0,0,0,0,10 ,0,0,0,0,0,10,0,0,0,0,0,10,0,0,0,0,0,10,0,0,0,0,0,10,0,0,0,0,0,10) period.5<-c(0,0,0,0,0,10,0,0,0,0,10,0,0,0,0,0,0,10,0,0,0,0,10,0,0,0,0,0,0,10 ,0,0,0,0,10,0,0,0,0,0,0,10,0,0,0,0,10,0,0,0,0,0,0,10,0,0,0,0,10,0) par(mfrow=c(2,1))
2003 Apr 15
1
About kruskal.test
Hi, I'm newbie in R package, but i'm extremely gratefull for these list! is there possible to make kruskal.test summarize the sum of ranks?? e.g ##### z<-c(1.2,3.4,0,0,0,0,0) ranks(z) # like in octave package ans= 6 7 3 3 3 3 3 sum(ranks(z)) ans= 28 ### then apply multiple comparisions for many other data SE<-sqrt(n*(n*k)*(n*k+1)/12) # according Zar,JH. Bioestatistical
2008 May 16
2
Box.test degrees of freedom
Dear colleagues, I am new to R and statistics so please keep that in mind. I have doubts on the df calculation of Ljung-Box test (Box.test). The function seems to use always the df=lag=m and not df=m-p-q like suggested in Ljung and Box (1978) paper (that is referenced). Do you agree with this? If so, is there an R package function that computes Ljung-Box test with the degrees of
2007 Nov 16
1
monthplot () - axis change color
Hi, When I run this code a part of my x-axis and y-axis changes color. Can somebody tell me what is wrong? Also, is there a way to control the color of the average lines? monthplot(AirPassengers+500, ylim=c(min(AirPassengers), max(AirPassengers+500)), ylab="") par(new=T) monthplot(AirPassengers, col="blue", ylim=c(min(AirPassengers), max(AirPassengers+500)),
2008 Jun 19
2
how to write symbol (nabla) in R graph
Dear colleagues, Can anyone of you tell me how to write a "nabla" symbol in an R graph? Thanks in advance, Nuno ______________________________________________ Centro de Oceanografia - IO-FCUL, Portugal Center for Quantitative Fisheries Ecology - ODU, USA [[alternative HTML version deleted]]
2011 Feb 21
3
assign value to multiple objects with a given ls pattern
Dear R colleagues, This seems pretty straight forward but I have been banging my head on this for some time and can't seem to find a solution suppose I have something like a1<-1; a2<-2; a3<-3; a4<-4; b1<-3; b2<-4 I would like to quickly assign to objects with a certain pattern, e.g., those in ls(pattern="a") a specific value, e.g., "99", without
2006 Jan 24
1
spec.pgram() normalized too what?
Dear list, What on earth is spec.pgram() normalized too? If you would like to skip my proof as to why it's not normed too the mean squared or sum squared amplitude of the discrete function a[], feel free too skip the rest of the message. If it is, but you know why it's not exact in spec.pgram() when it should be, skip the rest of this message. The issue I refer herein refers only too a
2006 Jan 24
3
R-help Digest, Vol 35, Issue 24
Dear Prof Ripley, First of all, unless you are an english professor, then I do not think you have any business policing language. I'm still very much a student, both in R, and regarding signal analysis. My competence on the subject as compared too your own level of expertise, or my spelling for that matter, may be a contension for you, but it would have been better had you kept that opinion
2008 Jan 15
3
How to interrupt a loop by pressing a key?
Hello, Does anyone know a way of interrupting a loop by pressing a key (besides ctrl-c)? My problem is the following: I have a machine acquiring data and saving text files into a directory. I have an R script that read those files, process them and plots the results. What I would like to do is: process the data as the files appear in the folder (I've done that do with a loop that checks
2009 Mar 31
1
Lomb periodograms
Hi, I have recently used the CTS package in order to use the Lomb-Scargle periodogram (spec.ls) function. I have noticed an issue that I hoped you may be able to explain. If a regularly spaced time series has two points removed, one at either side of a single data point (thus making an irregularly spaced time series), a spectrum with a very large peak at the highest frequencies is produced. An
2004 Sep 15
1
lomb periodogram package
Hi, Does anyone know the name of the package that includes a function for computing the lomb periodogram on irregular spaced ts data? I saw the package once ~ 1 month ago but cannot find it now ... , Rich
2009 Jun 19
1
typo in Lomb-Scargle periodogram implementation in spec.ls() from cts package?
Hello! I tried to contact author of the package, but I got no reply. That is why I write it here. This might be useful for those who were using cts for spectral analysis of non-uniformly spaced data. In file spec.ls.R from cts_1.0-1.tar.gz lines 59-60 are written as pgram[k, i, j] <- 0.5 * ((sum(x[1:length(ti)]* cos(2 * pi * freq.temp[k] * (ti - tao))))^2/sum((cos(2 * pi * freq.temp[k] *
2007 Nov 13
1
Discrimination of almost-random time series
Dear time-series specialist: I've got some time series representing measurements from a physical process, like atomic decay data. These time series look almost random, but should hopefully be distinguishable as they were taken under different conditions. I am looking for statistical approaches that are sensitive enough to discriminate between such series of measurements. Preferably, there
2008 Aug 01
1
Solving Yis[i] = a*cos((2*pi/T)*(times[i] - Tau)) + ...
Hi everybody, I am reading the Lomb paper (Lomb, 1976) and I found an interesting equation, and I wish to resolve it using R. I am wondering if anybody has a hint. The equation is: Yis[i] = a*cos((2*pi/T)*(Times[i] - Tau)) + b*sin((2*pi/T)*(Times[i] - Tau)) ... (1) Where T and Tau are constants. I know the "Times" and "Tis" values (in fact these values come from a Time
2011 May 28
0
how to train ksvm with spectral kernel (kernlab) in caret?
Hello all, I would like to use the train function from the caret package to train a svm with a spectral kernel from the kernlab package. Sadly a svm with spectral kernel is not among the many methods in caret... using caret to train svmRadial: ------------------ library(caret) library(kernlab) data(iris) TrainData<- iris[,1:4] TrainClasses<- iris[,5] set.seed(2)
2007 Nov 28
0
Power Spectral Sensity
I am working with a dissolved oxygen dataset. continuous readings are taken at 15 minute intervals and we have been recording these data at 12 stations along the savannah river for two years now. The longest set of readings that are continuous without interuption is 53 days. I would like to look at the power spectral density at each of these sites (most likely one day will be the overridding
2012 Mar 08
0
Cross-Power Spectral Density and Welch's Method
Hello to R uers, I am wondering if there is an easy way to perform a cross-power spectral density estimation of ?two timeseries (x and y) using the Welch's method. Both packages "bspec" and "oce" provide a function to calculate the PSD with the Welch's method, but only for a timeserie. Thank you in advance. Regards, Pascal
2012 Jan 22
1
Problem with sapa package and spectral density function (SDF)
Hi everybody, I'm a beginner R user and I'm trying to use the package "sapa" to estimate the spectral density function of several time series using the SDF function. For each time series, I want to calculate the density function at two temporal resolutions (daily and monthly). The monthly values calculated as a mean of the daily values. I first create a ts object for both series