Displaying 20 results from an estimated 5000 matches similar to: "Problems with the ts library"
2011 Oct 18
2
About an integral univariate problem
Hello all R users
I want to calculate this univariate integral:
exp(-x)*sum(y^x) respect to x from 0 to 3 where y is a vector y=(2,3,5).
In fact, the original y vector has a large number of elements but I propose
with 3 elements.
I know that I can resolve this problem doing
fun <- function(x) exp(-x)*(2^x+3^x+5^x)
integrate(fun,0,3)
When the y vector has a large number of elements the
1999 Aug 11
1
acf()
Hi there,
I have R 0.64.2. I wonder if this R has acf function to calculate
autocorrelation? since the help(acf) doesnt seem to be able to help me.
thanks,
Peppy
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1999 Jul 19
9
time series in R
Time Series functions in R
==========================
I think a good basic S-like functionality for library(ts) in base R
would include
ts class, tsp, is.ts, as.ts
plot methods
start end window frequency cycle deltat
lag diff aggregate
filter
spectrum, spec.pgram, spec.taper, cumulative periodogram, spec.ar?
ar -- at least univariate by Yule-Walker
arima -- sim, filter, mle, diag, forecast
2009 Oct 08
1
acf for a univariate time series in a data frame
hi everyone!
i want to check the autocorrelation function for a univariate time series
(streamflow) in a data frame as below:
< DF <- read.table("D:/file path....")
< DF
year jan feb mar apr ...... dec
1966 0.504 0.406 0.740 0.241 0.429
1967 0.683 0.529 0.780 0.443 0.503
.
.
.
.
what i first tried is:
acf (DF, plot = TRUE)
2003 Jul 15
1
function acf in package ts
Hi R lovers!
I'd like to know if the 2 blue lines in the graph produced by the function
acf in the package ts represents the level for the test of significance of
the autocorrelation
thanks for help
vincent
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2006 Mar 24
3
bug in plot.acf (PR#8705)
(Moved from r-devel to r-bugs)
On 3/24/2006 5:03 AM, Antonio, Fabio Di Narzo wrote:
> Hi all.
> There's a bug in plot.acf, when plotting acf for multivariate time series.
> Here a reproducible example:
>
> X <- rnorm(1000)
> Y <- -X + rnorm(1000, sd=0.6)
> Z <- cbind(X,Y)
>
> In
> acf(Z)
> cross-correlation plot y-axis is limited to 0-1. But:
>
1999 Jul 27
1
R hangs when hist() gets vector with a single value
Hi, I'm not sure if this is a bug or due to my ignorance of R syntax. I'm using
hist() to plot a sample set of data, some sets contain the same value (i.e.
3000, 3000, 3000, 3000). I find that hist() hangs when It gets to sets with a
single value. ....help ? ...victor
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2002 Feb 28
1
multiple replications of a ts
Hello
I have several replicates (30) of a -- short -- time series (19 obs) and
I'd like to estimate the first few lags autocorrelation function.
Is there an immediate way of handling multiple realizations when computing
the ACF in R?
I'm using R-1.4.1 on a Linux Debian box.
Thanks in advance
claudia
-------------------------------------------------------------------------
claudia
2006 Mar 23
2
Default lag.max in ACF
Hi,
The default value for lag.max in ACF implementation is 10*log10(N)
There several publications recommending setting lag.max to:
- N/4 (Box and Jenkins, 1970; Chatfield, 1975; Anderson, 1976;
Pankratz, 1983; Davis, 1986; etc.)
- sqrt(N)+10 (Cryer, 1986)
- 20<=N<=40 (Brockwell and Davis)
Why R uses 10*log10(N) as a default?
Please, give me a reference to a book or article where the
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
2004 Mar 05
2
Internal NA removal out of Time Series with na.omit.ts()
Hi R specialists,
The na.omit.ts() method fails when the time series contains internal
NA's. How can these automatically be removed?
> spectrum(ts.mNDII, na.action=na.omit)
Error in na.omit.ts(as.ts(x)) : time series contains internal NAs
How can the na.action be activated correctly?
> acf(ts.Lin, type=c("correlation"), na.action=na.omit)
Error in na.omit.ts(as.ts(x)) :
1997 Oct 29
4
R-beta: new executable
I have just put up a new executable as a replacement for the one in
rseptbeta.zip
there have only been a few changes; mostly to the menu's. I am about
to start on a major overhaul including getting survival to work and
grabbing the 0.60 version once it's stable.
Please let me know about other enhancements you want....
robert
1997 Oct 29
4
R-beta: new executable
I have just put up a new executable as a replacement for the one in
rseptbeta.zip
there have only been a few changes; mostly to the menu's. I am about
to start on a major overhaul including getting survival to work and
grabbing the 0.60 version once it's stable.
Please let me know about other enhancements you want....
robert
2008 Oct 28
1
acf() plots of a data.frame: what meaning?
Hello,
what is the meaning of the plots of an acf()-plot,
when using a data frame as argument?
The result is NOT obvious for me.
There are combinations of the columns of a dataframe in the reulting
plot.
But an acf() is just defined for onyl one time-sreies.
So what do the plots mean? I did not found a description in the
help-page.
Ciao,
Oliver
2007 Mar 07
1
good procedure to estimate ARMA(p, q)?
Hi all,
I have some residuals from regression, and i suspect they have correlations
in them...
I am willing to cast the correlation into a ARMA(p, q) framework,
what's the best way to identify the most suitable p, and q, and fit ARMA(p,
q) model and then correct for the correlations in regression?
I know there are functions in R, I have used them before, but I just want to
see if I can do
2002 May 08
1
ts acf accessing to values
Hi,
I don't quite understant how can I access to the acf values from the
list produced by the acf function
Example:
library(ts)
t <- acf(ts.union(ts(1:10), ts(11:20)))
t$acf
> tmp$acf
, , 1
[,1] [,2]
[1,] 1.00000000 1.00000000
[2,] 0.70000000 0.70000000
[3,] 0.41212121 0.41212121
[4,] 0.14848485 0.14848485
[5,] -0.07878788 -0.07878788
[6,] -0.25757576
2006 Aug 18
3
Query: how to modify the plot of acf
I need to modify the graph of the autocorrelation. I tried to do it through plot.acf but with no success.
1. I would like to get rid of the lag zero
2. I would like to have numbers on the x-axis only at lags 12, 24, 36, 48, 60, ...
Could anybody help me in this?
Any help will be appreciated
Thank you for your attention
Stefano
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2011 Sep 16
3
question concerning the acf function
Hi everyone,
I've got a question concerning the function acf(.) in R for calculating the
autocorrelation in my data.
I have a table with daily returns of several stocks over time and I would
like to calculate the autocorrelation for all the series (not only for one
time series). How can I do this?
After that I want to apply an autoregressive model based on the estimated
lag in the
2010 Apr 29
1
a question on autocorrelation acf
Hi R users,
where can I find the equations used by acf function to calculate
autocorrelation? I think I misunderstand acf. Doesn't acf use following
equation to calculate autocorrelation?
[image: R(\tau) = \frac{\operatorname{E}[(X_t - \mu)(X_{t+\tau} -
\mu)]}{\sigma^2}\, ,]
If it does, then the autocorrelation of a sine function should give a
cosine; however, the following code gives a
2010 Apr 17
2
interpreting acf plot
Hello,
I am attending a course in Computational Statistics at ETH and in one of the assignments I am asked to prove that a time series is not autocorrelated using the R function "acf".
I tried out the acf function with the given data, according to what I found here: http://landshape.org/enm/options-for-acf-in-r/ this test data does not look IID but rather shows some trends so how can I