Dan Bolser dmb at mrc-dunn.cam.ac.uk
Fri Jul 22 15:40:56 CEST 2005

```On Fri, 22 Jul 2005, Gabor Grothendieck wrote:

>Try as.expression(bquote(...whatever...))

Sob, wimper, etc.

my.slope.1 <-   3.22
my.slope.2 <-   0.13
my.inter.1 <- -10.66
my.inter.2 <-   1.96
my.Rsqua.1 <-   0.97

text(2,5,
paste("Slope:  ",
as.expression(bquote(.(my.slope.1)%+-%.(my.slope.2)))))

That puts the text and variable together, but not the symbol, which is
printed as '%+-%'

The following is nearly right, but wrong enough it makes my first attempt
look reasonable...

# Create the initial plot as per Christoph's post
plot(1:5, 1:5, type = "n")

legend(x=1,
y=4.5,
bg='white',
ncol=3,
c("Slope","Intercept",expression(R^2),
":",":",":",
bquote( .(my.slope.1)%+-%.(my.slope.2)),
bquote( .(my.inter.1)%+-%.(my.inter.2)),
my.Rsqua.1
)
)

Anyone got any ideas on how to fix the above?

Namely 1) right align numbers, 2) remove excessive white space.

I like the above because it dosn't require me to calculate exactly where
to put each piece of text.

I just want to annotate a plot :(

>
>
>On 7/22/05, Dan Bolser <dmb at mrc-dunn.cam.ac.uk> wrote:
>> On Thu, 21 Jul 2005, Marc Schwartz (via MN) wrote:
>>
>> >[Note: the initial posts have been re-arranged to attempt to maintain
>> >the flow from top to bottom]
>> >
>> >> >Dan Bolser writes:
>> >> > >
>> >> > > I would like to annotate my plot with a little box containing the slope,
>> >> > > intercept and R^2 of a lm on the data.
>> >> > >
>> >> > > I would like it to look like...
>> >> > >
>> >> > >  +----------------------------+
>> >> > >  | Slope     :   3.45 +- 0.34 |
>> >> > >  | Intercept : -10.43 +- 1.42 |
>> >> > >  | R^2       :   0.78         |
>> >> > >  +----------------------------+
>> >> > >
>> >> > > However I can't make anything this neat, and I can't find out how to
>> >> > > combine this with symbols for R^2 / +- (plus minus).
>> >> > >
>> >> > > Below is my best attempt (which is franky quite pour). Can anyone
>> >> > > improve on the below?
>> >> > >
>> >> > > Specifically,
>> >> > >
>> >> > > aligned text and numbers,
>> >> > > aligned decimal places,
>> >> > > symbol for R^2 in the text (expression(R^2) seems to fail with
>> >> > > 'paste') and +-
>> >> > >
>> >> > >
>> >> > >
>> >> > > Cheers,
>> >> > > Dan.
>> >> > >
>> >> > >
>> >> > > dat.lm <- lm(dat\$AVG_CH_PAIRS ~ dat\$CHAINS)
>> >> > >
>> >> > > abline(coef(dat.lm),lty=2,lwd=1.5)
>> >> > >
>> >> > >
>> >> > > dat.lm.sum <- summary(dat.lm)
>> >> > > dat.lm.sum
>> >> > >
>> >> > > attributes(dat.lm.sum)
>> >> > >
>> >> > > my.text.1 <-
>> >> > >   paste("Slope : ",     round(dat.lm.sum\$coefficients[2],2),
>> >> > >         "+/-",          round(dat.lm.sum\$coefficients[4],2))
>> >> > >
>> >> > > my.text.2 <-
>> >> > >   paste("Intercept : ", round(dat.lm.sum\$coefficients[1],2),
>> >> > >         "+/-",          round(dat.lm.sum\$coefficients[3],2))
>> >> > >
>> >> > > my.text.3 <-
>> >> > >   paste("R^2 : ",       round(dat.lm.sum\$r.squared,2))
>> >> > >
>> >> > > my.text.1
>> >> > > my.text.2
>> >> > > my.text.3
>> >> > >
>> >> > >
>> >> > > ## Add legend
>> >> > > text(x=3,
>> >> > >      y=300,
>> >> > >      paste(my.text.1,
>> >> > >            my.text.2,
>> >> > >            my.text.3,
>> >> > >            sep="\n"),
>> >> > >      cex=1
>> >
>> >
>> >> On Thu, 21 Jul 2005, Christoph Buser wrote:
>> >>
>> >> >Dear Dan
>> >> >
>> >> >paste. You can use:
>> >> >
>> >> >plot(1:5,1:5, type = "n")
>> >> >text(2,4,expression(paste("Slope : ", 3.45%+-%0.34, sep = "")), pos = 4)
>> >> >text(2,3.8,expression(paste("Intercept : ", -10.43%+-%1.42)), pos = 4)
>> >> >text(2,3.6,expression(paste(R^2,": ", "0.78", sep = "")), pos = 4)
>> >
>> >> >I do not have an elegant solution for the alignment.
>> >
>> >
>> >On Thu, 2005-07-21 at 19:55 +0100, Dan Bolser wrote:
>> >> Cheers for this.
>> >>
>> >> I was trying to get it to work, but the problem is that I need to replace
>> >> the values above with variables, from the following code...
>> >>
>> >>
>> >> dat.lm <- lm(dat\$AVG_CH_PAIRS ~ dat\$CHAINS)
>> >> dat.lm.sum <- summary(dat.lm)
>> >>
>> >> my.slope.1 <- round(dat.lm.sum\$coefficients[2],2)
>> >> my.slope.2 <- round(dat.lm.sum\$coefficients[4],2)
>> >>
>> >> my.inter.1 <- round(dat.lm.sum\$coefficients[1],2)
>> >> my.inter.2 <- round(dat.lm.sum\$coefficients[3],2)
>> >>
>> >> my.Rsqua.1 <- round(dat.lm.sum\$r.squared,2)
>> >>
>> >>
>> >> Anything I try results in either the words 'paste("Slope:", my.slope.1,
>> >> %+-%my.slope.2,sep="")' being written to the plot, or just
>> >> 'my.slope.1+-my.slope2' (where the +- is correctly written).
>> >>
>> >> I want to script it up and write all three lines to the plot with
>> >> 'sep="\n"', rather than deciding three different heights.
>> >
>> >
>> >> Thanks very much for what you gave, its a good start for me to figure out
>> >> how I am supposed to be telling R what to do!
>> >>
>> >> Any way to just get fixed width fonts with text? (for the alignment
>> >> problem)
>> >
>> >
>> >Dan,
>> >
>> >Here is one approach. It may not be the best, but it gets the job done.
>> >You can certainly take this and encapsulate it in a function to automate
>> >the text/box placement and to pass values as arguments.
>> >
>> >A couple of quick concepts:
>> >
>> >1. As far as I know, plotmath cannot do multiple lines, so each line in
>> >your box needs to be done separately.
>> >
>> >2. The horizontal alignment is a bit problematic when using expression()
>> >or bquote() since I don't believe that multiple spaces are honored as
>> >such after parsing. Thus I break up each component (label, ":" and
>> >values) into separate text() calls. The labels are left justified.
>> >
>> >3. The alignment for the numeric values are done with right
>> >justification. So, as long as you use a consistent number of decimals in
>> >the value outputs (2 here), you should be OK. This means you might need
>> >to use formatC() or sprintf() to control the numeric output values on
>> >either side of the +/- sign.
>> >
>> >4. In the variable replacement, note the use of substitute() and the
>> >list of x and y arguments as replacement values in the expressions.
>> >
>> >
>> >
>> >my.slope.1 <- 3.45
>> >my.slope.2 <- 0.34
>> >
>> >my.inter.1 <- -10.43
>> >my.inter.2 <- 1.42
>> >
>> >my.Rsqua <- 0.78
>> >
>> >
>> ># Create the initial plot as per Christoph's post
>> >plot(1:5, 1:5, type = "n")
>> >
>> >
>> >#-------------------------------------
>> ># Do the Slope
>> >#-------------------------------------
>> >
>> >text(1, 4.5,  "Slope", pos = 4)
>> >text(2, 4.5, ":")
>> >text(3, 4.5, substitute(x %+-% y,
>> >                        list(x = my.slope.1,
>> >                             y = my.slope.2)),
>> >     pos = 2)
>> >
>> >
>> >#-------------------------------------
>> ># Do the Intercept
>> >#-------------------------------------
>> >
>> >text(1, 4.25, "Intercept", pos = 4)
>> >text(2, 4.25, ":")
>> >text(3, 4.25, substitute(x %+-% y,
>> >                         list(x = my.inter.1,
>> >                              y = my.inter.2)),
>> >     pos = 2)
>> >
>> >
>> >#-------------------------------------
>> ># Do R^2
>> >#-------------------------------------
>> >
>> >text(1, 4.0, expression(R^2), pos = 4)
>> >text(2, 4.0, ":")
>> >text(3, 4.0,  substitute(x, list(x = my.Rsqua)),
>> >     pos = 2)
>> >
>> >
>> >#-------------------------------------
>> ># Do the Box
>> >#-------------------------------------
>> >
>> >rect(1, 3.75, 3, 4.75)
>> >
>> >
>> >You can adjust the x,y coordinates for the various text elements as you
>> >may require and can also calculate them based upon the xlim, ylim of
>> >your actual plot. You can also modify the 'cex' argument to text() for
>> >adjusting the sizes of the fonts in use.
>>
>>
>> I have been trying many different combinations of the suggestions so
>> far...
>>
>> bquote, substitute, expression, paste, etc.
>>
>> Also I was trying to use the 'expression' part of the 'legend' function to
>> make thing easier (make new lines, make columns, make rectangles)...
>>
>> So far all in vain.
>>
>> I am sure a fairly neat solution is possible using 'legend' and
>> 'expression', but I cant get a legend which contains a variable
>> substituted value *and* a special symbol.
>>
>> Can anyone show me an example of this simple step, and then I can try to
>> build on that.
>>
>>
>> Thanks all for suggestions, its one of those 'it seems so easy' problems
>> (for me).
>>
>> P.S. Whats with the documentation for bquote?
>>
>>
>>
>> >BTW, to use a monospaced font, you can set par(family = "mono").
>> >
>> >HTH,
>> >
>> >Marc Schwartz
>> >
>> >
>>
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