Plotting bar graph from website

Greetings,

I need help with plotting the bar graph from: NAO in Matlab.

I have downloaded the data for the graph from: Data with:

NAO = table2array(readtable(websave('AO.csv','https://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/monthly.ao.index.b50.current.ascii.table'),'ReadVariableNames',false));

I have tried plotting it with:

for i = 1:height(NAO)

    for j = 2:13

        bar(datetime(NAO(i),j-1,1),NAO(i,j),0.1,'b')
        hold on

    end

end

The plot then end up looking like 'graph.png'.

The first thing I would like to change is to remove the day from the datetime, but I don't know how to do that, especially in a for loop.

The second thing is the xaxis, why does only the first date show and not more dates?

Third thing is the color, why is it all black when I have set all bars to be blue? I want of course all the negative values to be red and all positive values blue but that's a problem for later.

So if anyone has any tips on how to proceed to plot the bar graph that would be great.

Thanks!

[Les Beckham]

I think you have an issue with the indexing, for one thing. Can you explain what the data is and what the columns and rows represent, and what you are trying to plot?

As far as the color is concerned, the bars are so narrow that you only see the EdgeColor (which is black by default), not the FaceColor. So, once you straighten out the indexing, change the bar command to something like

bar(..., 'FaceColor', 'b', 'EdgeColor', 'b')

Then the skinny bars will be blue.

[Walter Roberson]

In my test, the edge color did not default to black ([0 0 0]) but rather to [33 33 33]/256 which is about [0.1294 0.1294 0.1294]

[Les Beckham]

Interesting. I didn't check, I just assumed it was black because it looks black. [0.1294 0.1294 0.1294] is a pretty dark grey.

Answer 1

[Walter Roberson]

First:

ax = gca;
ax.XRuler.TickLabelFormat = 'mmm uuuu';

would change the format to (for example) "Jan 1960"

Third:

You have lots and lots and lots of bars. They are so thin (to fit them all) that all you can see of them is the outline. The default outline color appears to be [33 33 33]/255

Answer 2

[Peter Perkins]

Marcus, it looks to me like what you have is a year-by-month array.

As others have said, those bars are mightily thin. Have you considered plotting lines?

T = readtable(websave('AO.csv','https://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/monthly.ao.index.b50.current.ascii.table'),'ReadVariableNames',false);
T.Properties.VariableNames=["Date","Jan" "Feb" "Mar" "Apr" "May" "Jun" "Jul" "Aug" "Sep" "Oct" "Nov" "Dec"];
T2 = stack(T,2:13,"ConstantVariables",1,NewDataVariableName="X",IndexVariableName="Month");
T2.Date = datetime(T2.Date,repmat((1:12)',74,1),1);
T2.Month = [];
TT = table2timetable(T2);
plot(TT,"Date","X")

That is not exactly what you wanted, but not far. A stemplot seems useful:

stem(TT,"Date","X",Marker=".")

But if bar it must be:

bar(TT.Date,TT.X)