I had a dataset like this (in case someone wants to reproduce things).
dset <- structure(list(period = structure(c(15340, 15340, 15431, 15431, 15522, 15522, 15614, 15614, 15706, 15706, 15340, 15340, 15431, 15431, 15522, 15522, 15614, 15614, 15706, 15706), class = "Date"), mylevel = c("first", "second", "first", "second", "first", "second", "first", "second", "first", "second", "first", "second", "first", "second", "first", "second", "first", "second", "first", "second"), mygroup = c("first", "first", "first", "first", "first", "first", "first", "first", "first", "first", "second", "second", "second", "second", "second", "second", "second", "second", "second", "second"), myval = c(5.68927789934355, 12.4668435013263, 8.50574712643678, 9.21052631578947, 5.79964850615114, 11.864406779661, 6.63507109004739, 8.27067669172932, 7.60233918128655, 10.3030303030303, 11.5713243721996, 12.868193989884, 10.9409799554566, 12.2498118886381, 10.3649843170801, 13.6053288925895, 10.0093381580483, 13.4111885477491, 10.2109430074291, 11.9337016574586), mylower = c(4.27785665208779, 9.30578687083796, 6.73766221814479, 6.20777175527346, 4.02547019162226, 8.40474543043271, 5.05063053061992, 5.25570937453824, 5.91602875207158, 7.24127641498182, 11.1220283594508, 12.0765169377083, 10.4880238235312, 11.4706823400243, 9.86527996838732, 12.7476946734056, 9.5638481418534, 12.505411895047, 9.77751066855676, 11.14516485388), myupper = c(7.39412079167001, 16.2315194276058, 10.5605825092892, 13.036419049039, 8.04876321621977, 16.112730355332, 8.53001582404356, 12.2542112131, 9.58747177688514, 14.0992747034508, 12.0322972656053, 13.6922322688037, 11.4066255686044, 13.0622336650376, 10.8811950353039, 14.4984825068148, 10.4684536436971, 14.3573893347113, 10.6569666040485, 12.7574674651682)), .Names = c("period", "mylevel", "mygroup", "myval", "mylower", "myupper"), row.names = c(NA, 20L), class = "data.frame")
I needed a chart like the following:
Which I quickly obtained with the code:
(Note: I have an Italian locale--the months displayed are January, April, July and January again)
Since the period column is actually the first day of a quarter, I wanted to change the labels on the x-axis to quarters, with the help of the zoo package.
However, when I submitted the code:
library(zoo) ggplot(data=dset, aes(x=period, y=myval)) + geom_line(lwd=1, aes(col=mygroup)) + geom_ribbon(aes(ymin=mylower, ymax=myupper, fill=mygroup), alpha=.5) + facet_grid(mylevel ~ .) + xlab("period") + ylab("value") + scale_x_continuous(breaks=unique(dset$period) , labels=dset$dtFrom) + theme(legend.title = element_blank())
I got the following error:
Error: Discrete value supplied to continuous scale
After some time of trials and errors, I discovered a way to get to my desired results, which requires the conversion of dates to numbers.
ggplot(data=dset, aes(x=as.integer(period), y=myval)) + geom_line(lwd=1, aes(col=mygroup)) + geom_ribbon(aes(ymin=mylower, ymax=myupper, fill=mygroup), alpha=.5) + facet_grid(mylevel ~ .) + xlab("period") + ylab("value") + scale_x_continuous(breaks=as.integer(unique(dset$period)) , labels=unique(as.yearqtr(dset$dtFrom))) + theme(legend.title = element_blank())
And here's my desired result.
I don't know if there is a less awkward way to get the chart above. Let me know in the comments below if I missed something obvious.
