dates on xaxis are not readable

Question

I have a data frame that has dates, disk reads and disk writes data. I am able to create the stack chart but the dates on xaxis are not readable. Is there an option in qplot to scale the graph or dont display all of the dates or something? I've been looking at this now for a long time, I couldn't find an answer.

I melt it first

app1_diskIO.M<-melt(app1_diskIO.M, id=c("Date2"))

qplot(x = factor(Date2), y = value, data = app1_diskIO.M, geom = "bar", fill = variable, main="DISK IO", xlab="Date", ylab="Disk IO")

Data frame looks like this:

       Date2 DiskReads DiskWrites
1  2011-12-06  136382.2    78961.0
2  2011-12-07  146277.0    77802.0
3  2011-12-08  141123.6    76219.0
4  2011-12-09  139219.8    77649.4
5  2011-12-10   72101.1    35258.6
6  2011-12-11  229445.9    92316.6
7  2011-12-12  175886.7    86087.0
8  2011-12-13  134958.3    76605.6
9  2011-12-14  133972.1    75141.4
10 2011-12-15  147175.2    77189.7
11 2011-12-16  143542.3    78155.9
12 2011-12-17  152579.1    68395.2
13 2011-12-18  168667.7    69720.1
14 2011-12-19  152328.6    75994.2
15 2011-12-20  135061.8    75271.6
16 2011-12-21  153455.0    78197.5
17 2011-12-22  130020.8    73369.7
18 2011-12-23  131423.6    73484.9
19 2011-12-24  135285.6    65081.4
20 2011-12-25  137185.4    63334.8
21 2011-12-26  132612.9    70484.4
22 2011-12-27  155396.9    79239.1
23 2011-12-28  151587.5    77986.5
24 2011-12-29  122076.5    71575.5
25 2011-12-30  146888.8    75376.3
26 2011-12-31  141285.5    69737.8
27 2012-01-01  206306.6    78059.4
28 2012-01-02  134002.4    73062.5
29 2012-01-03  137753.8    76947.4
30 2012-01-04  150655.8    78836.3
31 2012-01-05  151750.3    79300.9
32 2012-01-06  141464.8    77529.4
33 2012-01-07  137667.3    66344.8
34 2012-01-08  120998.5    60582.4
35 2012-01-09  133422.4    73688.3
36 2012-01-10  134247.7    75664.5
37 2012-01-11  146243.5    79042.2
38 2012-01-12  178738.2    84199.7
39 2012-01-13  145564.8    77908.2
40 2012-01-14  135966.8    65900.9
41 2012-01-15  136448.4    63339.9
42 2012-01-16  186109.9    83348.6
43 2012-01-17  146906.5    78645.6
44 2012-01-18  106343.0    69313.6
45 2012-01-19  197205.6    88411.6
46 2012-01-20  132950.1    73078.0
47 2012-01-21  137488.1    68711.5

Instead of cutting and pasting what your data frame looks like, run the command `dput(app1_diskIO.M)` which will output the code to construct your data frame. Everyone can just cut and paste it into their R. — nograpes, Mar 16 '12 at 17:43

score 1 · Accepted Answer · edited May 23 '17 at 12:07

How about rotating the dates to be vertical, that makes them a bit more legible:

qplot(x = factor(Date2), y = value, data = app1_diskIO.M, 
     geom = "bar", fill = variable, main = "DISK IO", 
     xlab = "Date", ylab = "Disk IO") +
     opts(axis.text.x = theme_text(angl e =-90))

enter image description here

You could also reduce the font size (is that what you mean by scale?), but that doesn't make it any easier to read. To do this, add a size argument in the opts

qplot(x = factor(Date2), y = value, data = app1_diskIO.M, 
     geom = "bar", fill = variable, main = "DISK IO", 
     xlab = "Date", ylab = "Disk IO") +
     opts(axis.text.x = theme_text(angle = -90, size = 5))

To remove all tick marks and labels on X axis (so you're not displaying any dates, as you request, maybe you might use a graphics editor to put something else there?), try this:

qplot(x = factor(Date2), y = value, data = app1_diskIO.M, 
     geom = "bar", fill = variable, main = "DISK IO", 
     xlab = "Date", ylab = "Disk IO")  + 
     opts(axis.ticks = theme_blank(), axis.text.x = theme_blank())

UPDATE: To space out the x axis labels, say one every ten days, as you request, try this:

app1_diskIO.M$Date2 <- as.Date(app1_diskIO.M$Date2)
qplot(x = Date2, 
      y = value, data = app1_diskIO.M, 
      geom = "line", colour = variable, 
      main="DISK IO", xlab="Date", 
      ylab="Disk IO") +
      scale_x_date(breaks = "10 days") +
      opts(axis.text.x = theme_text(angle = -90))

Which should give you:

enter image description here

Useful website with excellent instructions for doing this kind of stuff: http://wiki.stdout.org/rcookbook/Graphs/Axes%20(ggplot2)/

The guide to the updates in ggplot2 0.9 is very handy too, with lots of good examples: http://cloud.github.com/downloads/hadley/ggplot2/guide-col.pdf

Related question: need to create a stack bar chart

still xaxis not readable, is there a way to put may be dates for every 10 days? — user1272594, Mar 16 '12 at 18:09
I get this error: Error in get(x, envir = this, inherits = inh)(this, ...) : unused argument(s) (breaks = "10 days") — user1272594, Mar 19 '12 at 13:16
You might have an older version of `ggplot2`. The use of the `breaks` argument like this is new to 0.9, which just came out earlier this month. Try updating or re-installing `ggplot2` and see if that helps — Ben, Mar 19 '12 at 21:10

dates on xaxis are not readable

1 Answers1