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I would like to include minor brakes in my chart such that the full date is printed at the beginning of every month, and days are marked just by a tick on the x axis. What I have right now does not retrieve errors but the output is not what I want, since there are no ticks for the days.

library(ggplot2)

df <- data.frame(date=as.Date(1:60,origin = "1970-01-01"),value=rnorm(60,4,3))
str(df)
ggplot()+
  geom_line(data=df, aes(x=date, y=value))+
  scale_x_date(date_breaks = 'month', date_minor_breaks = 'day')

session:

other attached packages:
[1] scales_0.4.0  cowplot_0.6.2 ggplot2_2.1.0 dplyr_0.5.0   zoo_1.7-13

This issue has been discussed in Formatting dates with scale_x_date in ggplot2 but I wonder if something changed in the meanwhile since if I follow the code that was suggested

scale_x_date(breaks = "1 month", minor_breaks = "1 week", labels=date_format("%B"))

I actually get an error

> ggplot()+
+   geom_line(data=df, aes(x=date, y=value))+
+   scale_x_date(breaks = "1 month", minor_breaks = "1 week", labels=date_format("%B"))
Error in strsplit(unitspec, " ") : non-character argument
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Dambo
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1 Answers1

3

I am not sure what your error is, because this isn't a reproducible sample.

The following code works on my computer and gives you weekly ticks. 

ggplot() +
     geom_line(data=df, aes(x=date, y=value)) +
     scale_x_date(date_breaks = "1 week", 
                   date_minor_breaks = "1 day",)

You can change the formatting of the weekly label by using the date_labels argument, e.g., using %D gives you m/d/y, as follows. 

ggplot() +
     geom_line(data=df, aes(x=date, y=value)) +
     scale_x_date(date_breaks = "1 week", 
                    date_minor_breaks = "1 day",
                    date_labels = "%D")

and you can change the aesthetic of the ticks by using the theme layer. For example, changing to the following will give you longer or bigger ticks. 

   ggplot() +
     geom_line(data=df, aes(x=date, y=value)) +
     scale_x_date(date_breaks = "1 week", 
                   date_minor_breaks = "1 day",) +
    theme(axis.text.x=element_text(size=10),
          axis.ticks = element_line(size = .5),
          axis.ticks.length = unit(.2, "cm"))

Edited: Following your comment, I think this is what you want. Not sure why but it looks a little "ugly" to me. Hope this helps. 

library(lubridate) 
not_first_of_the_month<- which(duplicated(floor_date(df$date, "month")))
xlabels <- as.character(df$date)
xlabels[not_first_of_the_month] <-rep("", length(not_first_of_the_month))

ggplot() +
     geom_line(data=df, aes(x=date, y=value)) +
               scale_x_date(breaks = df$date,
                            labels = xlabels,
               date_minor_breaks = "1 day")
shayaa
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  • There are no errors I would like to have one tick per each day tho. However, only months should be labelled. – Dambo Jul 24 '16 at 01:23
  • I edited my answer. Did this give you what you wanted? – shayaa Jul 24 '16 at 22:21
  • ?lubridate::floor_date – shayaa Jul 25 '16 at 01:03
  • So thanks yes, the last script is what I was trying to do. I actually thought that `minor_breaks` drew smaller ticks, which would be aesthetically a bit more appealing. Maybe I missed something in the documentation but is wasn't fully clear to me that that attribute operates on the background grid lines. If you wanna leave the first part of your answer that's since my question was probably unclear, but I was actually interested in the last part only. – Dambo Jul 25 '16 at 01:19
  • Ya, I'll leave it, but I hunched what you might have been wanting, that's why I included the blurb on themes. – shayaa Jul 25 '16 at 01:24