Ignacio Ignacio - 3 months ago 73
R Question

ggplot2 scale x date?

I would like to make the ticks in the following graph daily instead of every 2 days.

df1 <- structure(
list(
Timestamp = structure(
c(
1441837436, 1441843661,
1441885583, 1441966341, 1441985621, 1442048926, 1442321691, 1442329081,
1442349761, 1442408140, 1442417679, 1442508871, 1442513339, 1442513395,
1442514010, 1442525088, 1442553226, 1442562304
), tzone = "UTC", class = c("POSIXct",
"POSIXt")
), number = 7:24
), class = "data.frame", row.names = c(NA,-18L), .Names = c("Timestamp", "number")
)

ggplot(df1, aes(x = Timestamp, y = number)) +
geom_line(size=2) + geom_point(size=5) +
scale_y_continuous(breaks = seq(0, 50, by = 2))


I tried adding
+ scale_x_date(breaks = "1 day")
but I get the following error:

Error: Invalid input: date_trans works with objects of class Date only


I also tried
scale_x_datetime(limits=c(as.POSIXct('2015-09-09'), as.POSIXct('2015-09-19')), breaks = 1)





ggplot(df1, aes(x = Timestamp, y = number)) +
geom_line(size=2) + geom_point(size=5) + scale_x_datetime(breaks = "1 day")
Error in strsplit(unitspec, " ") : non-character argument


does not work either :(




I tried in two different computers:

> sessionInfo()
R version 3.2.2 (2015-08-14)
Platform: x86_64-pc-linux-gnu (64-bit)
Running under: Debian GNU/Linux 8 (jessie)

locale:
[1] LC_CTYPE=en_US.UTF-8 LC_NUMERIC=C
[3] LC_TIME=en_US.UTF-8 LC_COLLATE=en_US.UTF-8
[5] LC_MONETARY=en_US.UTF-8 LC_MESSAGES=en_US.UTF-8
[7] LC_PAPER=en_US.UTF-8 LC_NAME=C
[9] LC_ADDRESS=C LC_TELEPHONE=C
[11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C

attached base packages:
[1] stats graphics grDevices utils datasets
[6] methods base

other attached packages:
[1] ggplot2_1.0.1.9003 taucharts_0.3.2
[3] dplyr_0.4.3 fasttime_1.0-1
[5] lubridate_1.3.3 readr_0.1.1

loaded via a namespace (and not attached):
[1] Rcpp_0.12.1 digest_0.6.8
[3] assertthat_0.1 grid_3.2.2
[5] plyr_1.8.3 R6_2.1.1
[7] gtable_0.1.2 DBI_0.3.1
[9] magrittr_1.5 scales_0.3.0.9000
[11] stringi_0.5-5 lazyeval_0.1.10
[13] RColorBrewer_1.1-2 tools_3.2.2
[15] stringr_1.0.0 htmlwidgets_0.5
[17] munsell_0.4.2 parallel_3.2.2
[19] colorspace_1.2-6 htmltools_0.2.6
[21] memoise_0.2.1


2.

> sessionInfo()
R version 3.2.1 (2015-06-18)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows 7 x64 (build 7601) Service Pack 1

locale:
[1] LC_COLLATE=English_United States.1252 LC_CTYPE=English_United States.1252 LC_MONETARY=English_United States.1252
[4] LC_NUMERIC=C LC_TIME=English_United States.1252

attached base packages:
[1] stats graphics grDevices utils datasets methods base

other attached packages:
[1] dplyr_0.4.3 ggplot2_1.0.1.9003

loaded via a namespace (and not attached):
[1] colorspace_1.2-6 scales_0.3.0.9000 lazyeval_0.1.10 magrittr_1.5 R6_2.1.1 assertthat_0.1
[7] plyr_1.8.3 parallel_3.2.1 DBI_0.3.1 tools_3.2.1 gtable_0.1.2 Rcpp_0.12.1
[13] grid_3.2.1 munsell_0.4.2

Answer

You can use the scales package. It looks like you need to use the function date_breaks, rather than just breaks to get proper labels:

EDIT: it appears the argument has been changed to date_breaks:

library(scales)
library(ggplot2)
ggplot(df1, aes(x = Timestamp, y = number)) +
    geom_line(size=2) +
    geom_point(size=5) + 
    scale_y_continuous(breaks = seq(0, 50, by = 2)) + 
    scale_x_datetime(date_breaks = "1 day")

original:

library(scales)
library(ggplot2)
ggplot(df1, aes(x = Timestamp, y = number)) +
    geom_line(size=2) +
    geom_point(size=5) + 
    scale_y_continuous(breaks = seq(0, 50, by = 2)) + 
    scale_x_datetime(breaks = date_breaks("1 day"))

enter image description here

If you want to change how the date is displayed in the label, you can use date_format inside the scale_x_datetime call.