[BUGZILLA #17527] stats::window() fails with start argument

[MichaelChirico]

Say we have a monthly time series starting from year 1998. We want to obtain the last value via window() function:

x = ts(1:20, start = 1998, frequency = 12)                                    
x                                                                             

 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec                                                                                                                                                                                           

1998 1 2 3 4 5 6 7 8 9 10 11 12
1999 13 14 15 16 17 18 19 20

window(x, start = c(1999, 8), end = c(1999, 8))

 Aug

1999 20

which is equivalent of

window(x, start = c(1999, 8))                                                 

 Aug                                                                                                                                                                                                                                       

1999 20

Now if we start the time series from A.D. 1,

x2 = ts(1:20, start = 1, frequency = 12)                                      
x2                                                                            

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
1 1 2 3 4 5 6 7 8 9 10 11 12
2 13 14 15 16 17 18 19 20

window(x2, start = c(2, 8), end = c(2, 8))

Aug
2 20

which is fine. But

window(x2, start = c(2, 8))                                                   

Error in window.default(x, ...) : 'start' cannot be after 'end'

sessionInfo()

R version 3.5.2 (2018-12-20)
Platform: x86_64-pc-linux-gnu (64-bit)
Running under: Debian GNU/Linux 9 (stretch)

Matrix products: default
BLAS/LAPACK: /usr/lib/x86_64-linux-gnu/libmkl_rt.so

locale:
[1] LC_CTYPE=en_US.UTF-8 LC_NUMERIC=C LC_TIME=en_US.UTF-8
[4] LC_COLLATE=en_US.UTF-8 LC_MONETARY=en_US.UTF-8 LC_MESSAGES=en_US.UTF-8
[7] LC_PAPER=en_US.UTF-8 LC_NAME=C LC_ADDRESS=C
[10] LC_TELEPHONE=C LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C

attached base packages:
[1] stats graphics grDevices utils datasets methods base

loaded via a namespace (and not attached):
[1] compiler_3.5.2

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METADATA

• Bug author - Feng Li
• Creation time - 2019-01-30 14:58:17 UTC
• Bugzilla link
• Status - UNCONFIRMED
• Alias - None
• Component - Analyses
• Version - R 3.5.0
• Hardware - All All
• Importance - P5 normal
• Assignee - R-core
• URL -
• Modification time - 2019-11-25 12:59 UTC

[MichaelChirico]

This seems to be a floating point issue. On my computer, when end is not present and the row name is 2 as in the example, the function calculates it with 2 + 7/12 shown as 2.5833333. This is greater than the value from the tsp[2] 2.583333. When end is provided it is 2.583333 (the same as from tsp[2]).

For the x example 1999.583 is for both the tsp[2] and (1999 + 7/12).

If in window.default() we changed the check to something like (start > end & !all.equal(start, end, .001)) that would work for this case, but obviously has other implications.

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METADATA

• Comment author - elin.waring
• Timestamp - 2019-11-25 12:59:57 UTC