Displaying 20 results from an estimated 10000 matches similar to: "Cross correlations on many imported files."
2009 Apr 20
2
Cross-Correlation function (CCF) issues
Dear all,
I have two series of returns and I want to find the cross-correlations
between these two series. I know of the ccf, but it does not work as I'd
like
if i type
ccf(x,y,lag.max=20,type="correlation",plot=FALSE)
i got the error message
Error in na.fail.default(ts.intersect(as.ts(x), as.ts(y))) :
missing values in object
So i found that somebody suggested to type
2012 May 11
1
Possible artifacts in cross-correlation function ("ccf")?
Dear R-users,
I have been using R and its core-packages with great satisfaction now for many years, and have recently started using the "ccf" function (part of the "stats" package version 2.16.0), about which I have a question.
The "ccf"-algorithm for calculating the cross-correlation between two time series always calculates the mean and standard deviation per time
2010 Apr 13
0
ccf problem (cross-correlation)
Hi all,
I have a problem concerning my understanding of the cross-correlation (ccf)
function in R.
assume a time serie as:
> t<-seq(0,6.28,by=0.01);
> my_serie<-ts(sin(t),start=0,end=6.28,deltat=0.01)
then I generate an other one shifted by 12 time points:
> my_shifted_serie<-ts(sin(t),start=0+0.12,end=6.28+0.12,deltat=0.01)
if I do the cross-correlation I get that the two
2011 Mar 11
1
Partial Cross Correlation
Does anyone know of any R code for computing partial cross-correlation? I have examples of cross correlation functions (ccfs) that are not smooth but rather consist of a peak of several high values in consecutive lags, with sharp drops on either side. This indicates that y(t) is a function of some average of x(t-tau) at the set of lags tau over which the ccf is high. I could sort out these
2014 Nov 04
1
[R] Calculation of cross-correlation in ccf
Dear All,
I am studying some process measurement time series in R and trying to identify time delays using cross-correlation function ccf. The results have however been bit confusing. I found a couple of years old message about this issue but unfortunately wasn't able to find it again for a reference.
For example, an obvious time shift is observed between the measurements y1 and y2 when the
2005 Oct 31
1
how to optimise cross-correlation plot to study time lag between time-series?
Dear R-help,
How could a cross-correlation plot be optimized such that the relationship
between seasonal time-series can be studied?
We are working with strong seasonal time-series and derived a
cross-correlation plot to study the relationship between time-series. The
seasonal variation however strongly influences the cross-correlation plot
and the plot seems to be ?rather? symmetrical (max
2005 Oct 20
1
Cross-correlation function
Hello All,
I'm having trouble with the ccf() function. I am trying to do cross-correlation between two time-series, but I keep getting an error message I don't know what to do with. This what I type and the error message I get:
> ccf(ts(mod[,1]),ts(mod[,2]),na.action='na.exclude',type='cor')
Error in "colnames<-"(`*tmp*`, value = c("ts(mod[,
2013 Jan 29
1
ccf (cross correlation function) problems
Hello everybody,
I am sorry if my questions are too simple or not easily understandable. I’m
not a native English speaker and this is my first analysis using this
function.
I have a problem with a cross correlation function and I would like to
understand how I have to perform it in R.
I have yearly data of an independent variable (x) from 1982 to 2010, and I
also have yearly data of a variable
2009 Jan 20
2
Confidence intervals in ccf()
Hi,
I have been running the ccf() function to find cross-correlations of time
series across various lags. When I give the option of plot=TRUE, I get a
plot that gives me 95% confidence interval cut-offs (based on sample
covariances) for my cross-correlations at each lag. This gives me a sense of
whether my cross-correlations are statistically significant or not.
However, I am unable to get R to
2006 Aug 30
1
Cross-correlation between two time series data
Hi all,
I have two time series data (say x and y). I am interested to
calculate the correlation between them and its confidence interval (or
to test no correlation). Function cor.test(x,y) does the test of no
correlation. But this test probably is wrong because of autocorrelated
data.
ccf() calculates the correlation between two series data. But it does
not
2006 Mar 02
1
CCF and Lag questions
I am new to R and new to time series modeling.
I have a set of variables (var1, var2, var3, var4, var5) for which I have
historical yearly data.
I am trying to use this data to produce a prediction of var1, 3 years into
the future.
I have a few basic questions:
1) I am able to read in my data, and convert it to a time series format
using 'ts.'
data_ts <- ts(data, start = 1988, end =
2007 Jan 08
1
query
Hello!
I found the ccf function gives different estimates than the simple lag correlations.
Why is that?
This is my code:
set.seed(20)
x<-rnorm(20)
y<-x+rnorm(20,sd=0.3)
print("R CCF:")
print(ccf(x,y,lag.max=2,plot=F))
myccf<- c( cor(y[-(1:2)],x[-(19:20)]) , cor(y[-1],x[-20]),
cor(y,x),
cor(x[-1],y[-20]),cor(x[-(1:2)],y[-(19:20)]) )
2008 Mar 05
1
Need help for calculating cross-correlation between 4 multivariate time series data
Hi all,
I would like to know whether there is any function in R were i can
find the cross-correlation of two or more multivariate (time series) data. I
tried the function ccf() but it seems like to have two univariate datasets.
Please let me know.
sincerely,
sandeep
--
Sandeep Joseph PhD
Post Doctoral Associate
Center for Tropical & Emerging Global Diseases
Paul D. Coverdell Center,
1999 Jul 08
1
new time series package available
Fritz just put the first version of a new time series package to the
contrib section at CRAN.
The package is called "tseries.tgz" and provides a library for time
series analysis. It contains
acf Autocorrelation Function
adf.test Augmented Dickey-Fuller Test
amif Auto Mutual Information Function
bds.test BDS Test
1999 Jul 08
1
new time series package available
Fritz just put the first version of a new time series package to the
contrib section at CRAN.
The package is called "tseries.tgz" and provides a library for time
series analysis. It contains
acf Autocorrelation Function
adf.test Augmented Dickey-Fuller Test
amif Auto Mutual Information Function
bds.test BDS Test
2009 Jun 15
2
GARCH:: False Convergence
Dear R users,
I am trying to use tseries' garch function in order to determine the
volatility of a return series generated by quantmod. Here is the code that I
am using:
> library(quantmod)
> getSymbols("AAPL")
convert daily closing prices into continuous log returns
> dret<-dailyReturn(AAPL,type='log')
check to see that the autocorrelations decay
>
2005 Jun 10
0
Top N correlations from 'cor' for very large datasets being run many times
I am doing an analysis that requires me to calculate correlations for a matrix of 15,000 rows x 50 columns. For each row I want to calculate the correlation to all other rows and then for each row, find the n (say 10) most correlated rows. If read in the 15,000 x 50 data from file and pass it to 'cor', this function quite appropriately (and very quickly) calculates all possible row by
2006 Mar 23
1
Cross correlation in time series
Hi list,
I'm working on time series of (bio)physical data explaining (or not) the
net ecosystem exchange of a system (+_ CO2 in versus CO2 out balance).
I decomposed the time series of the various explaining variable
according to scale (wavelet decomposition). With the coefficients I got
from the wavelet decomposition I applied a (multiple) regression, giving
some expected results. The net
2011 Jun 30
0
CCF of two time series pre-whitened using ARIMA
Hi all,
I have two time series that I would like to correlate but as they are
autocorrelated, I am "pre-whitening" them first by fitting ARIMA models,
then correlating their residuals....as described in
https://onlinecourses.science.psu.edu/stat510/?q=node/75
However, http://www.stat.pitt.edu/stoffer/tsa2/Rissues.htm discusses some
issues with ARIMA in R. In particular, for issue 2, if
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