[R] barplot beside=TRUE - values differ on scales

[Duncan Murdoch]

On 12/10/2016 12:20 PM, Adrian Johnson wrote:
> Dear group,
> I have been struggling to barplot two different measurements from one
> subject. These two measures differ in range.  I want to plot row 1
> axis on left side and row 2 values on right side.
>
> For a given column I want to plot GN and CN next to each other.
>
> my dput code is below
> :
>
> structure(c(112L, 0L, 579L, 1L, 131L, 1L, 2234L, 2L, 2892L, 1L,
> 528L, 0L, 582L, 2L), .Dim = c(2L, 7L), .Dimnames = list(c("GN",
> "CN"), c("DC5", "DC8", "DC14", "DC18", "DC19", "DC20", "DC23"
> )))
>
>
> As you can see:
>     DC5 DC8 DC14 DC18 DC19 DC20 DC23
> GN 112 579  131 2234 2892  528  582
> CN   0   1    1    2    1    0    2
>
> GN values are range from 100 - 3000
> while CN are always -2 or -1 or 0 or 1 or 2
>
> Also I cannot log GN values and plot because a difference in 100 units
> also matters in my experiment.
>
> Any help would be greatly appreciated.

I would simply rescale one row and add a second axis.  For example, if d 
holds your matrix:

scale <- max(d[1,])/max(d[2,])
adjusted <- d
adjusted[2,] <- scale*adjusted[2,]
barplot(adjusted, beside = TRUE)
ticks <- pretty(d[2,])
axis(side = 4, at = ticks*scale, labels = ticks)

Duncan Murdoch