[R] [Q] use of expression() in plot() vs. hist()

[Peter Dalgaard BSA]

George White <gwhite at bodnext.bio.dfo.ca> writes:

> > First of all, I don't know where people are getting that paste()
> > construction from. The juxtaposion operator for plotting math is "*",
> > i.e. 
> > 
> > hist(c(0,0,0,0,4,5,6,6,6,8), xlab=expression("scaled "*rho))
> > 
> The use of "paste" comes from careful reading of the documentation:
> 
> > ?legend
> [...]
>      ex.cs1 <- expression(plain(sin) * phi,  paste("cos", phi))# 2 ways
>      legend(-3, .9, ex.cs1, lty=1:2, col=2:3)
> 
> "paste" and "*" are both used in "?text" as well.

I might have checked....

Anyways, there's clearly a bug in the implementation of paste(), so
'*' should be used for now.

Specifically:

static BBOX RenderConcatenate(SEXP expr, int draw)
{
    BBOX bbox;
    int i, n;

    expr = CDR(expr);
    n = length(expr);

    for (i = 0; i < n; i++) {
        bbox = CombineBBoxes(bbox, RenderElement(CAR(expr), draw));
        if (i != n - 1)
        ....

starts with an uninitialised bbox, which looks unhealthy to me.

-- 
   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)             FAX: (+45) 35327907
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