minor_breaks function ignored

[baptiste]

## setting numeric values for minor_breaks works:

qplot(10^(1:6), 10^(1:6)) + scale_x_log10(breaks = 10^(1:6),
  minor_breaks = log(c(sapply(10^(1:6), function(x) seq(0, x, x/10))), 10))) 

## but a function is ignored:

qplot(10^(1:6), 10^(1:6)) + scale_x_log10(breaks = trans_breaks("log10", function(x) 10^x, n=6) ,
   minor_breaks = trans_breaks("log10", function(x) 10^x, n=60) )

the minor breaks disappear entirely.

[kohske]

Actually that is not ignored, but simply out of range.

qplot(10^(1:6), 10^(1:6)) + scale_x_log10(breaks = trans_breaks("log10", function(x) 10^x, n=6) ,
   minor_breaks = trans_breaks("log10", function(x) log(10^x, 10), n=60) )

will work.

The breaks internally transform the data, while the minor breaks do not.
I know it's confusing.

[baptiste]

oh, I see, thanks. I think it would be much less confusing to have the same behavior as major breaks. Also, the example you submitted

qplot(10^(1:6), 10^(1:6)) + scale_x_log10(breaks = 10^(1:6),
minor_breaks = log(c(sapply(10^(1:6), function(x) seq(0, x, x/10))), 10))

would be quite useful in the documentation for scale_x_log10.

[hadley]

We probably need a little documentation for scale_breaks_minor describing exactly what it does.

[kohske]

We probably need a little documentation for scale_breaks_minor describing exactly what it does.

Who is going to?

[hadley]

I'll do it - either today or tomorrow. (Note to self: also make sure to document minor_breaks arguments to date scales)

[hadley]

Hmmm, this is more complicated than I thought. Ideally, we should be able to wrap the default behaviour (n evenly spaced minor breaks between each major break) into a standard minor breaks function - but currently it needs both the major breaks and the limits. This may suggest that the minor breaks function should get both those arguments - but then all other minor breaks functions will need to be rewritten (e.g. for date and date time).

We also need someway to easily control the number of minor breaks between major breaks.

[hadley]

See exploration in minor_breaks branch: https://github.com/hadley/ggplot2/compare/minor_breaks

[kohske]

We also need someway to easily control the number of minor breaks between major breaks.

ggplot2 may have its own number + unit representation (at least internally).

e.g.,

minor_breaks = c(0, 1, 2) # raw numeric
minor_breaks = ggunit(1, "count") # number of minor breaks between major breaks
minor_breaks = ggunit(-1, "level") # in the case of date/datetime, if major breaks = month, minor = week.

I imagine this function would be useful in many places.

[kohske]

of course ggunit is a simple function like this:

ggunit <- function(value, unit = "I", ...) 
  structure(value, class = "ggunit", unit = unit, ...)

[kohske]

ggunit is available also for data space identifier. like:

breaks = ggunit(c(1:10), "transformed")
breaks = ggunit(c(1:10), "original")

the name ggunit should be reconsidered, though.

[hadley]

I think this is big enough that I'm going to put it off until 0.9.1

[hadley]

And now until 0.9.2

[chmullig]

It appears this is still in 0.9.3.

[hadley]

This sounds like a great feature, but unfortunately we don't currently have the development bandwidth to support it. If you'd like to submit a pull request that implements this feature, please follow the instructions in the development vignette.