[Rd] "plot.ts" doesn't respect the value of "pch" (+ blocked from Bugzilla signups)

[Martin Maechler]

>>>>> Gregory Werbin <greg.werbin at libertymail.net>
>>>>>     on Thu, 25 Aug 2016 15:21:05 -0400 writes:

    > I've had a chance to read the source more thoroughly. The chain of 
    > events is as follows:

    > 1. Local function `plotts()` is defined with argument `cex` that 
    > defaults to `par("cex")`
    > 2. `...` is passed to `plotts()`. If "cex" is an element in `...`, 
    > inside `plotts()` the variable `cex` is assigned thereby (overriding the 
    > default arg). Importantly, this means that the element "cex" is captured 
    > and _removed_ from `...`. `...` is eventually passed to `plot.window()`.
    > 3.
    > - In the univariate case (NCOL(x) == 1): When `lines.default()` is 
    > called to actually plot the data 
    > (https://github.com/wch/r-source/blob/trunk/src/library/stats/R/ts.R#L588 
    > and 
    > https://github.com/wch/r-source/blob/trunk/src/library/stats/R/ts.R#L597 
    > for reference), `cex` is not included in the call.
    > - In the bivariate case (NCOL(x) > 1): Because "cex" was captured and 
    > removed from `...`, it is not passed to `plot.default` when it is called 
    > (https://github.com/wch/r-source/blob/trunk/src/library/stats/R/ts.R#L548).

    > It turns out that the "eating" is not being done by `...` but by the 
    > signature of `plotts`.

    > The documentation currently reads:

    >> ...: additional graphical arguments, see 'plot', 'plot.default' and 
    >> 'par'.

    > This, to me, suggests parity with the 'plot' function in how the 
    > arguments in '...' are handled. Therefore either the code is wrong or 
    > the documentation is incomplete and misleading.

the code is not perfect aka "wrong" .. so the bug is there.
Making the minimal reproducible example more concise,

 plot(as.ts((-10:12)^3), type="b", cex=.5)
 plot(     ((-10:12)^3), type="b", cex=.5)

should plot identically ... but currently don't


    > I filed this is as a bug because it's undocumented, and inconsistent 
    > with how other arguments typically passed through `plot.default` are 
    > handled.

    > I'll be happy to do the patch myself -- I just need to know which thing 
    > to patch (the source or the docs).

[yes... and please subscribe to bugzilla which I told you
 yesterday I had explicitly opened for you !]

Martin
 
    > Greg


    > On 2016-08-25 03:00, David Winsemius wrote:

    >>> On Aug 24, 2016, at 5:59 PM, Gregory Werbin 
    >>> <greg.werbin at libertymail.net> wrote:
    >>> 
    >>> I did a search on Bugzilla for "plot.ts" and didn't find anything on 
    >>> this issue. I tried to sign up for Bugzilla to report it, but my 
    >>> e-mail address didn't pass your "syntax checking" for a legal e-mail 
    >>> address.
    >>> 
    >>> The bug is easily reproducible on my machine as follows:
    >>> 
    >>> ## start
    >>> 
    >>> # generate some data
    >>> y <- arima.sim(list(), 150)
    >>> 
    >>> # this will definitely dispatch to a ".ts" method
    >>> class(y)[1] == 'ts'
    >>> 
    >>> # compare and note that `cex = 0.5` has no effect
    >>> plot(y, type = 'b', pch = 16)
    >>> plot(y, type = 'b', pch = 16, cex = 0.5)
    >>> 
    >>> # it works if `y` is coerced back to a regular vector
    >>> plot(as.numeric(y), type = 'b', pch = 16, cex = 0.5)
    >>> 
    >>> # another way to see the issue
    >>> plot.ts(y, type = 'b', pch = 16, cex = 0.5)
    >>> plot.default(y, type = 'b', pch = 16, cex = 0.5)
    >>> 
    >>> ## end
    >>> 
    >>> Skimming through source code for `plot.ts`, it seems like the `cex` 
    >>> argument is being "eaten" by a `...` somewhere without being properly 
    >>> passed to `plot.default`.
    >> 
    >> '...' does not "eat" parameters, it passes them on.
    >> 
    >> Looking at the very top of the body we see this in the definition of 
    >> the internal `plotts` function:
    >> 
    >> cex = par("cex"), lty = par("lty"), lwd = par("lwd"),
    >> axes = TRUE, frame.plot = axes, ann = par("ann"), cex.lab = 
    >> par("cex.lab"),
    >> col.lab = par("col.lab"), font.lab = par("font.lab"),
    >> cex.axis = par("cex.axis"), col.axis = par("col.axis"),
    >> 
    >> And at the end of the body we se the call to plotts (including the 
    >> "dots")
    >> 
    >> So I would suggest using par-settings.
    >> 
    >> par(cex=0.5)
    >> plot(y, type = 'b', pch = 16)
    >> 
    >> (Question seems more appropriate for r-help.)
    >> 
    >> --
    >> David.
    >> 
    >>> The output of `R.version` is:
    >>> platform       x86_64-apple-darwin15.5.0
    >>> arch           x86_64
    >>> os             darwin15.5.0
    >>> system         x86_64, darwin15.5.0
    >>> status
    >>> major          3
    >>> minor          3.1
    >>> year           2016
    >>> month          06
    >>> day            21
    >>> svn rev        70800
    >>> language       R
    >>> version.string R version 3.3.1 (2016-06-21)
    >>> nickname       Bug in Your Hair
    >>> 
    >>> Greg
    >>> 
    >>> ______________________________________________
    >>> R-devel at r-project.org mailing list
    >>> https://stat.ethz.ch/mailman/listinfo/r-devel
    >> 
    >> David Winsemius
    >> Alameda, CA, USA

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