Math Forum Discussions

Gordon Robertson

Posts: 14
Registered: 11/15/07

ChartLabels for Stacked, Grouped BarCharts?
Posted: Dec 20, 2009 6:54 AM

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Could I ask for help with ChartLabels for Stacked and Grouped BarCharts in
Mathematica 7? I've checked the MathGroup archives and Mathematica help docs.

I need to assess Stacked and Grouped BarCharts for a 2D dataset that
consists of 20 groups of three values. Labels for the groups are
{31,32,...,50}. From the help docs, it's easy to display the bars in either
mode for simple baseline cases. But I don't see how to put a *single* label
or tick *per stack or group*, below the X-axis.

The following simulates the 2D dataset that will be read in from a file:
tab2 = {{"a",1,2,3},{"b",2,3,4},{"c",3,4,5}}

labs2 = tab2[[All,1]]

data2 = tab2[[All,2;;4]]

I need "Stacked" and "Grouped" BarCharts that have "a","b" and "c",
respectively, as the labels for the three bar stacks or groups, below the
X-axis. The following commands do not give this:
BarChart[data2,ChartLayout->"Stacked",ChartLabels->Placed[labs2,Below]]
BarChart[data2,ChartLayout->"Grouped",ChartLabels->Placed[labs2,Below]]

The "Stacked" graph has a vertical stack of "a" "b" and "c" below the lower
edges of *each* block in *each* bar/block stack; the "Grouped" graph has a
label beneath *each* bar. Likely this makes sense in terms of general 'list '
rules, but it does not deliver what I need.

I've tried expanding the label list and using a list that includes None for
the second argument of Placed[], but have not quickly found a solution.

I can guess that Ticks may be the approach to use, but wonder if I could as k
more experienced folks for help. Could I also ask WRI to implement (or
document) these BarChart use cases.

Thanks in advance for your help in this.

Gordon
--
Gordon Robertson
BC Cancer Agency Genome Sciences Centre
Vancouver BC Canada
www.bcgsc.ca
604-707-5800 x675416