Fine-tuning the date axis in your bar chart


In these modern times, my utility bill has a bar chart so I can see how my current consumption compares to my historical usage. I decided to create my own version of this utility bill bar chart, and make a few improvements along the way. If you're into SGplot bar charts, you might learn a thing or two from this example!

But first, you need to guess what kind of utility data I'll be plotting. Is it water, sewer, power, or gas?!? Here's a hint, in the form of a picture my friend Annie took - very cool photo, eh?!?

And now, let's plot my power utility data! I grabbed one of my old power bills, and created a SAS dataset of the values shown in their graph. They don't give a specific date (just the month), but I went ahead and called it the first of the month in my dataset, to make it a valid 'date' value ...

And with the code below, here's my first bar chart of the data. Notice that I use the monyy7. date format, so the dates just show the month and year (not the '01' day part). I also used group=billmonth, to make the current/billing month's bar a different color than the other months.

title1 h=13pt "kWh Usage History";
proc sgplot data=my_data noborder noautolegend;
format date monyy7.;
styleattrs datacolors=(cxcad5e4 gray55);
vbarparm category=date response=kwh / group=billmonth
   outlineattrs=(color=gray77) tip=(date kwh);
yaxis display=(nolabel noline noticks) thresholdmax=1
  valueattrs=(weight=bold size=13pt)
   grid gridattrs=(color=graydd);
xaxis display=(nolabel noticks)
   fitpolicy=rotate valuesrotate=vertical;

That's an ~OK plot, but I think the date values along the bottom are a bit difficult to read (since I had to rotate them to make them fit), and having the year repeated so many times seems a bit wasteful of space. So let's apply the monname3. format to make the date values print as the 3-character month abbreviation. Those values will be short enough to fit under the bars without rotating. It looked good at first, but then I noticed that since the plot covers a 13 month time span, the graph has 2 September's (from 2 years) ... and when you plot the bars by the 3-character month abbreviation, the 2 Sep's get stacked into the same bar!

One advantage of the newer SGplot over the old SAS/Graph Gchart is that it has more "time smarts" built into it. Therefore I added the type=time option on the xaxis statement, to let it know to handle the values in a "time smart" way, and voilà - I got a chart with a very nicely formed time axis!

Now that we've got the graph looking great, let's create the rest of the power-bill look. They had a logo and address at the top of the bill - how can you add something like that to a SAS graph?!? ... By using annotate, of course! First, use the pad option to add some blank space above the graph:

I then used the following code to create the annotate dataset, and specified sganno=anno_all to include it in the SGplot bar chart.

data anno_logo;
length function $10 anchor $20 drawspace $20;
x1=2; y1=91;
widthunit='percent'; width=31.5;
heightunit='percent'; height=7;

data anno_address;
length label $100 x1space y1space $50;
function="text"; textcolor="gray33"; textsize=12;
width=100; widthunit='percent';
y1=86.5; label="JOHN DOE"; output;
y1=y1-5; label="123 SOME DRIVE"; output;
y1=y1-5; label="CARY, NC 27513-3322"; output;

data anno_all; set anno_logo anno_address;

proc sgplot data=my_data noborder noautolegend pad=(top=26pct) sganno=anno_all;



Hopefully you've learned a few tricks you can use in your own graphs! ... If you'd like to play around with this graph, here's a link to the complete SAS code. And if you're interested in utilities & energy, and would like to see more blog posts on this topic, click here.



About Author

Robert Allison

The Graph Guy!

Robert has worked at SAS for over a quarter century, and his specialty is customizing graphs and maps - adding those little extra touches that help them answer your questions at a glance. His educational background is in Computer Science, and he holds a BS, MS, and PhD from NC State University.

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  1. Thanks for the great demonstration - but I have a couple of questions.

    1. Why is your energy use much greater in the summer compared with the winter?

    2. Is there a "season" format that could be used to show this?

    • Robert Allison

      I use more electricity in the summer because I have an electric air conditioner (and less in the winter because I have gas heat).

      I'm not sure if SAS has a 'season' date format, but in this case I would rather have the bars labeled by month. I could perhaps use colored bands behind the bars to represent season.

  2. This is great....I have monthly data, can you explain how I would only show tickmark labels for every 2 months, yet continue to display all the data by month?

    • Dan Heath

      On the XAXIS statement, specify INTERVAL=MONTH and INTERVALMULT=2. This basically means you want 2-month intervals along the axis. Hope this helps!

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