I'd like to produce a step plot using ggplot2. I have datetime along the x-axis, and four discrete non-numeric factor levels on the y-axis. I'd like a line with steps between the levels where appropriate, but right now the code i've produced in ggplot2 isn't working. Any advice greatly appreciated!
So far I have the following code:
ggplot(s2, aes(x = datetime, y = activity)) + geom_step(colour = "blue")
which produces:
However, what I'd like is something that looks like this (I switched to geom_point, which works fine, and added the step lines by hand):
Here's a subset of my data, as a data.frame with with datetime (POSIXct) and activity (factor):
s2 <- structure(list(`datetime` = structure(c(1496102400L,
1496109600L, 1496116800L, 1496124000L, 1496131200L, 1496138400L,
1496145600L, 1496152800L, 1496160000L, 1496167200L, 1496174400L,
1496181600L, 1496188800L, 1496196000L, 1496203200L, 1496210400L,
1496217600L, 1496224800L, 1496232000L, 1496239200L, 1496246400L,
1496253600L, 1496260800L, 1496268000L, 1496275200L, 1496282400L,
1496289600L, 1496296800L, 1496304000L, 1496311200L, 1496318400L,
1496325600L, 1496332800L, 1496340000L, 1496347200L, 1496354400L,
1496361600L, 1496368800L, 1496376000L, 1496383200L, 1496390400L,
1496397600L, 1496404800L, 1496412000L, 1496419200L, 1496426400L,
1496433600L, 1496440800L, 1496448000L, 1496455200L), class = c("POSIXct",
"POSIXt"), tzone = "UTC"), activity = structure(c(1L, 2L, 3L,
4L, 4L, 4L, 4L, 4L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,
1L, 1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L,
2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L), .Label = c("HO",
"TR", "FO", "SE"), class = "factor")), .Names = c("datetime",
"activity"), row.names = c(NA, -50L), class = "data.frame")