How to make a bar chart, with x-labels and legend, directly from a table of listed data

Question

I have a data table tb that looks something like this, which I want to turn into a bar chart.

N         X       P   
________  ______  ______

0          5      15.314   
0         10      36.288   
0         13      7.1785   
1          5      18.182   
1         10      40.997   
1         13      8.9741   
2          5       17.65   
2         10      40.095   
2         13       9.276

I want the bar chart to look something like this, but without needing to rearrange the table. What is the simplest way to do this?

Currently, my code to do it looks like this, but I expect there should be an easier way to manipulate it:

y = [tb.P(tb.X==5)' ; tb.P(tb.X==10)' ; tb.P(tb.X==13)'];
b = bar(y);
xlab = arrayfun(@num2str, Xlist, 'uniformoutput', false);
set(gca,'xticklabel',xlab);
leg = arrayfun(@num2str, Nlist, 'uniformoutput', false);;
legend(b,leg)

What would be the proper method for doing this?

Answer 1

You can do this a little easier with unique and accumarray:

[nValues, ~, nIndex] = unique(tb.N);
[xValues, ~, xIndex] = unique(tb.X);
bar(accumarray([xIndex nIndex], tb.P));
set(gca, 'XTickLabel', xValues);
legend(int2str(nValues));