minor_breaks with Dates

[ptoche]

Is the following expected behaviour? (scroll down to the last example, which fails)

    df <- data.frame(
        x_date  = seq(as.Date("1952-01-01"), as.Date("2013-12-01"), by = "1 month"),
        y = runif(12*62)
    )
    library('ggplot2')
    library('scales')
    p <- ggplot(df, aes(x_date, y)) + geom_point()

    # version 1: automatic selection of start/end 'major' breaks
    p + scale_x_date(labels = date_format("%Y"), 
                     breaks = "5 years", 
                     minor_breaks = "1 year")

    # version 2: manual selection of start/end 'major' breaks
    p + scale_x_date(labels = date_format("%Y"), 
                     breaks = seq(as.Date("1950-01-01"), 
                                  as.Date("2015-01-01"), 
                                  by = "5 years"),
                     minor_breaks = "1 year")

    # version 3: manual selection of start/end 'minor' breaks: FAIL
    p + scale_x_date(labels = date_format("%Y"), 
                     breaks = seq(as.Date("1950-01-01"), 
                                  as.Date("2015-01-01"), 
                                  by = "5 years"),
                     minor_breaks = seq(as.Date("1975-01-01"), 
                                  as.Date("1995-01-01"), 
                                  by = "1 year"))
    ## Error in Ops.Date((x - from[1]), diff(from)) : 
    ##  / not defined for "Date" objects

[hadley]

This was a pretty major bug affecting minor_breaks whenever you used a transformed scale.