How to plot lines for each category in a table?

Suppose I have a table with three columns: a date, a categorical array, and values that vary by date and category. For example, the table may contain the annual GDP growth for the US, England, and Japan from 1980 - 2014. So, the date column would have three copies of 1980:2014 stacked on top of each other; the categorical array would have a label for the country for each set of years; and, the values would be the GDP growth for the given date and country.

Is there an easy (one line) way to plot all three country's GDP series (years on the x-axis, GDP growth on the y-axis) on the same chart using the categorical array?

Answer 1

[Geoff Hayes]

Why do you need a one line command to plot the data since there are only three countries? Can't you do something like the following to plot the GDP for each country?

 % get the unique countries
 countryNames = unique(myTable.Country);

 figure;
 hold on;
 for k=1:length(countryNames)
     % get the row indices for the kth country
     rowIdcs = strcmpi(myTable.Country,countryNames{k});
     % get the years for this country
     years = myTable.Year(rowIdcs);
     % get the GDP
     gdpPerYear = myTable.GDP(rowIdcs);
     % plot the data
     plot(years,gdpPerYear,'color',rand(1,3));
 end
 legend(countryNames);

The above is untested (since I don't have your table) but you should be able to modify the above to suit your needs.

[MBledsoe]

Thanks for the swift reply, Geoff. I figured that I could write a loop to do it, but I was hoping there was a simpler way, like how you can do scatter plots or box plots by group with one command (gscatter and boxplot, respectively).

[Peter Perkins]

A minor point: since Country is a categorical, this line

rowIdcs = strcmpi(myTable.Country,countryNames{k})

can be written as

rowIdcs = myTable.Country == countryNames{k}

[MBledsoe]

I want a one line command, because in reality, my table has multiple "value" columns and several categories.