[R] Add text/numbers to x axis?

[Peter Dalgaard]

Robert Lundqvist <Robert.Lundqvist at ltu.se> writes:

> Is there any simple way to add text to the x axis in R? I have tried to
> add simple characters in R without any greater sucess. As an example of
> what I want to do is the added C in the following "dumb" plot (produced
> with MacAnova using the option "dumb:T"):
> 
>     ++------+-------+------+-------+------+-------+------+-------++
>    1+                              :                             *+
>     |                              :                       *  *   |
>     |                              :                 *  *         |
>     |                              :              *  .            |
>  0.8+                              :           *     .            +
>     |                              :                 .            |
>     |                              :        *        .            |
>     |                              :     *           .            |
>  0.6+                              :                 .            +
>     |                              :  *              .            |
>     |                              *                 .            |
>     |                              :                 .            |
>     |                           *  :                 .            |
>  0.4+                              :                 .            +
>     |                        *     :                 .            |
>     |                     *        :                 .            |
>     |                              :                 .            |
>  0.2+                  *           :                 .            +
>     |               *              :                 .            |
>     |         *  *                 :                 .            |
>     |*  *  *                       :                 .            |
>    0++------+-------+------+-------+------+-------+--.---+-------++
>     -2    -1.5     -1    -0.5      0     0.5      1  C  1.5      2
> 
> 
> My attempts to use locator() and text() in R's plot() has not been working
> as good as expected. Never really knows where the added symbols end up...

mtext() is your friend.
 
> BTW, anyone who knows how such "dumb" plots could be achieved in R? This
> option is avaliable in S, so a port to R shouldn't be impossible, should
> it? Don't know how to do it myself however...

Presumably you "just" need someone to write a device driver for it.
The structure of those is somewhat different from S, so it's not a
straightforward port (even if the S code was publically available).
As I recall it (fortunately, it was decades ago), some cosmetic issues
become tricky due to the high granularity of such line printer plots;
things like alignment of strings and continuation of polylines.
However if someone wants to read up on Bresenham's line drawing
algorithm and all that...

-- 
   O__  ---- Peter Dalgaard             Øster Farimagsgade 5, Entr.B
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