Dropping time series observations

For class 'ts' the 'window' function in the base package will do it.

x <- ts(101:117, start=2001.75, frequency=4)
x

Qtr1 Qtr2 Qtr3 Qtr4
2001                 101
2002  102  103  104  105
2003  106  107  108  109
2004  110  111  112  113
2005  114  115  116  117

window(x, start=2002.5)

Qtr1 Qtr2 Qtr3 Qtr4
2002            104  105
2003  106  107  108  109
2004  110  111  112  113
2005  114  115  116  117

window(x, end=2002.5)

Qtr1 Qtr2 Qtr3 Qtr4
2001                 101
2002  102  103  104



Bill Dunlap
TIBCO Software
wdunlap tibco.com

On Sat, Jan 31, 2015 at 11:16 AM, Mikael Olai Milh?j <mikaelmilhoj at gmail.com

wrote:

Hi

Is there an easy way to drop, for instance, the first 4 observation of a
time series object in R? I have tried to google the answer without any
luck.

To be more clear:
Let us say that I have a time seres object x which data from 2000Q1 to
2014Q4 but I only want the data from 2001Q1 to 2014Q4.How do I remove the
first four elements?

By using x[5:?] R no longer recognize it as a ts.object.

Thank you

Best regards

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On Sat, Jan 31, 2015 at 2:16 PM, Mikael Olai Milh?j

Hi

Is there an easy way to drop, for instance, the first 4 observation of a
time series object in R? I have tried to google the answer without any
luck.

To be more clear:
Let us say that I have a time seres object x which data from 2000Q1 to
2014Q4 but I only want the data from 2001Q1 to 2014Q4.How do I remove the
first four elements?

By using x[5:?] R no longer recognize it as a ts.object.

1.  We could convert it to a zoo series, drop the first 4 and convert back:

For example, using the built in presidents ts series:

library(zoo)
as.ts(tail(as.zoo(presidents), -4))

1a. This would work too:

library(zoo)
as.ts(as.zoo(presidents)[-(1:4)])


2. Using only base R one can use window like this since 4 observations
is one cycle (given that the frequency of the presidents dataset is 4.

window(presidents, start = start(presidents) + 1)

or in terms of 4:

window(presidents, start = start(presidents) + 4 * deltat(presidents))

Here deltat is the time between observations so we want to start 4
deltat's later.

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