Displaying 20 results from an estimated 20000 matches similar to: "setting search position"
2001 Oct 09
3
Unlisting while preserving object types?
Hi
A toy example is probably the least ambiguous way of explaining what I'm
trying to do.
> library(ts)
> zz<-list(a=rnorm(100),b=rt(100,3))
> zz.spec<-lapply(zz,spectrum,plot=F)
> summary(zz.spec)
Length Class Mode
a 15 spec list
b 15 spec list
I'm looking for an elegant way to fetch components of the sub-lists a and b
of zz.spec;
e.g. to make a matrix
1999 Jul 27
3
Preliminary version of ts package
There is now a preliminary version of a time series package in the R-devel
snapshots, and we would welcome feedback on it. It is based in part on the
packages bats (Martyn Plummer) and tseries (Adrian Trapletti) and in part
on code I had or have written. (Thanks for the contributions, Martyn and
Adrian!) Some of the existing ts code has been changed, for example to plot
multiple time series, so
2006 Feb 02
0
How do I normalize a PSD?
Dear Tom,
Short answer, if your using spec.pgram(), use the smoothing kernel to get a
better estimate at the frequency centered in the bandwidth. If your
frequency bin of interest is wider than the bandwidth of the kernel, average
across frequencies (I think). The estimate appears to be normalized already.
If you are calculating your PSD independently, then oversample (e.g. 2,
perhaps 4 or more
2006 Jan 31
1
How do I "normalise" a power spectral density
I have done a fair bit of spectral analysis, and hadn't finished collecting my thoughts for a reply, so hadn't replied yet.
What exactly do you mean by normalize?
I have not used the functons periodogram or spectrum, however from the description for periodogram it appears that it returns the spectral density, which is already normalized by frequency, so you don't have to worry about
2010 Jan 11
1
HoltWinters Forecasting
Hi R-users,
I have a question relating to the HoltWinters() function. I am trying to
forecast a series using the Holt Winters methodology but I am getting some
unusual results. I had previously been using R for Windows version 2.7.2 and
have just started using R 2.9.1. While using version 2.7.2 I was getting
reasonable results however upon changing versions I found I started to see
unusual
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
2011 Jul 11
1
Spectral Coherence
Greetings,
I would like to estimate a spectral coherence between
two timeseries. The stats : spectrum() returns a coh matrix
which estimates coherence (squared).
A basic test which from which i expect near-zero coherence:
x = rnorm(500)
y = rnorm(500)
xts = ts(x, frequency = 10)
yts = ts(y, frequency = 10)
gxy = spectrum( cbind( xts, yts ) )
plot( gxy $ freq, gxy $
2005 Jun 03
0
noise poser spectral density
Dear Signal Processing Expert,
I would like to generate a random stationary signal of gaussian probability density function to simulate narrow band noise at the output of an IF amplifier. I know the receiver's system temperature (Ts) and IF bandwidth (B) therefore I assume that my narrow band noise mean power equals KTsB watts and therefore the power spectral density No=KTs per Hz.
Do you
2004 Jun 22
2
question about window and inserting value
Hi again R People:
I have the following time series:
>x.ts
Jan Feb Mar Apr May Jun Jul Aug Sep
2000 0.95 0.66 0.83 0.66 -1.45 -1.25 0.33 1.03 -0.48
2001 2.55 1.21 -1.10 -0.63 0.01 -2.20 -0.51 1.12 1.11
2002 -1.37 0.55 -0.63 -0.56 0.92 -1.73 0.59 0.77 0.30
2003 0.55 -0.01 -0.54 2.27 -1.29 -0.23 0.09 -0.50 -0.61
Oct Nov Dec
2000 0.84 -1.35
2000 Sep 23
2
Units
I used the AR modelling written for R (S) on blood pressure and heart rate
signals. I used 60 one second samples and a model order of 20. I used the
"ar" finction in the "ts" package.
Given that blood pressure is measured in mmHg would the spectral density (on
the graph displayed be [mmHg]sq/Hz ?
And the heart rate is measured in Beats Per Minute (bpm) - so would the
2003 Sep 03
2
problem with HoltWinters
Dear helpers
I'm having a problem with function HoltWinters from package ts. I have a time series that I want to fit an Holt-Winters model and make predictions for the next values. I've already built an object of class ts to serve as input to HoltWinters. But then I get an error; I've used HoltWinters a lot of times and this never hapened
> data.HW<-HoltWinters(data.ts)
Error
1998 Jun 23
0
samba: DEC UNIX password problem
I've just installed a new DEC Unix 4.0d machine and downloaded the binary
version of samba 1.9.18p8 for DEC Unix. I am able to get it up and running,
but I am having problems with passwords. I am being prompted for a password
when I try to connect to a non-public share, and when I type in my password it
is being rejected. I did set security=share in my smb.conf file. I also tried
the
2011 Feb 23
1
building zipped package with windows
Dear list,
i would like to build an own package using:
R CMD INSTALL --html --build --auto-zip -l folder spectral.methods
it seems to succeed as I get the following messages:
* installing *source* package 'spectral.methods' ...
** R
** data
Warning: empty 'data' directory
** preparing package for lazy loading
** help
*** installing help indices
converting help for package
2003 Jul 30
2
STL- TimeSeries Decomposition
Dear R Helpers,
Currently I'm working with the ts package of R and created a TimeSerie
from pixels extracted from satellite imagery(S10 NDVI data, 10 daily
composites). I'm trying to decompose this signal in different signals
(seasonal and trend).
When testing out the STL method is says => Only univariate timeseries
are allowed, but the current Timeserie I'm using is univariate!
2004 May 20
2
irregular time series
Background:
OS: Linux Mandrake 9.1
release: R 1.9.0
editor: Xemacs 21.4
frontend: ESS 5.1.23
---------------------------------
Colleagues
I have two time series (upwelling index and water temperature) of evenly
spaced, daily data over 18 months, but the upwelling index series has a gap
of about 2 months right in the middle of it. I want to do the acf, pacf,
ccf, and a cross-spectral analysis
2008 Dec 03
2
Spectral Analysis of Time Series in R
Dear R Community,
I am currently student at the Vienna University of Technology writing my
Diploma thesis on causality in time series and doing some analyses of
time series in R. I have the following questions:
(1) Is there a function in R to estimate the PARTIAL spectral coherence
of a multivariate time series? If yes, how does this work? Is there an
test in R if the partial spectral
2007 Jan 08
2
Simple spectral analysis
Hello world,
I am actually trying to transfer a lecture from Statistica to
R and I ran into problems with spectral analysis, I think I
just don't get it 8-(
(The posting from "FFT, frequs, magnitudes, phases" from 2005
did not enlighten me)
As a starter for the students I have a 10year data set of air
temperature with daily values and I try to
get a periodogram where the annual
2002 Oct 22
3
Spectral phase information in residue vectors
I found this sentence in the Ogg format specs:
http://www.xiph.org/ogg/vorbis/doc/vorbis-spec-res.html
"A residue vector may represent spectral lines, spectral magnitude, spectral phase or hybrids as mixed by channel coupling."
But where does the spectral phase information come from ?
AFAIK MDCT doesn't provide any phase information.
And in OGG-encoding, MDCT is taking place a few
2008 Jun 04
2
estimate phase shift between two signals
Hi,
Are there any functions in R that could be used to estimate the phase-shift
between two semi-sinusoidal vectors? Here is what I have tried so far, using
the spectrum() function -- possibly incorrectly:
# generate some fake data, normalized to unit circle
x <- jitter(seq(-2*pi, 2*pi, by=0.1), amount=pi/8)
# functions defining two out-of-phase phenomena
f1 <- function(x)
2012 Oct 23
1
find similarity between two spectral profile
Hi,
I'm Pina and I'm a student in geology. I'm working with spectral profile of
sand and I have to find the similarity between one spectral profile selected
by hyperspectral image anche one that I created to mix different percentage
of 4 mineral component. I have to find the best mix of percentage of this 4
mineral in order to have the best likeness with the spectral profile chose
by