add text to value of a plot, part 2

I have a plot with x axis takes the value January 1, January 2, .... and y axis takes the temperature of that day. In the x axis, I want to have these days and add a text "day" to these values so that they will be "Day 1 (January 1)","Day 2 (January 2)", "Day 3 (January 3)",... I did not find a relevant post on the Internet.

Answer 1

[Star Strider]

That needs a different approach.

Try this:

x = 1:10
y = rand(1,10);

figure
plot(x, y)
xt = get(gca, 'XTick');
xtklbl = sprintfc('Day %d (January %d)', [xt; xt]');
set(gca, 'Xtick',xt, 'XTickLabel',xtklbl, 'XTickLabelRotation',30)

You can also use the compose function in place of sprintfc (undocumented).

[alpedhuez]

Thank you. Will you explain how your code works? In the example I gave above January 1 is the 1st day, January 2 is the 2nd day,.. but it is a coincidence. I would like to have one that works with

column 1: date,...

column 2: 1,2,3,...

[Star Strider]

My pleasure.

The code works as printing a matrix with sprintf or fprintf. The documentation for them explains that, so I will not go into it here.

I do not understand what you want from the description you gave.

Try this:

x = 1:10
y = rand(1,10);
figure
plot(x, y)
xt = get(gca, 'XTick');
xtklbl = sprintfc('Day %d %d', [xt; randi([10 99],size(xt))]');
set(gca, 'Xtick',xt, 'XTickLabel',xtklbl, 'XTickLabelRotation',30)

with the ‘column 1’ numbers being the first row of the matrix, and the ‘column 2’ numbers being the second row of the matrix, where the matrix I refer to is:

[xt; randi([10 99],size(xt))]'

and for multiple-row tick labels (if that is what you want) try this:

x = 1:10;
y = rand(1,10);

figure
plot(x, y)
xt = get(gca, 'XTick');
xtklbl = {sprintfc('Day %d', xt); sprintfc('(January %d)', xt)};
set(gca, 'Xtick',xt, 'XTickLabel',xtklbl{1}, 'FontSize',9)
text(xt, (min(ylim)-0.05*diff(ylim))*ones(size(xt)), xtklbl{2}, 'HorizontalAlignment','center', 'VerticalAlignment','top', 'FontSize',7)

You can change the ‘xtklbl’ sprintfc calls to print anything you want. It is necessary to use text objects to print tick labels that do not correspond to the available options, such as multiple-line tick labels.

.

[alpedhuez]

Thanks. The intent is to have both col1 and col2 in values of x axis and to have the name of the months that also change from January to February,...

[Star Strider]

As always, my pleasure!

‘The intent is to have both col1 and col2 in values of x axis ...’

That is relatively straightforward, and (if I understand correctly) the first code snippet in my previous Comment.

‘... and to have the name of the months that also change from January to February,...’

That would likely require using a datetime object if it was to be fully adaptable.

It is not obvious to me how to do all of them together, unless it is some combination of what I have already done.

[alpedhuez]

Thank you very much. My question can be rephrased as follows. A spreadsheet has

column 1 = EST

colume 2 = PST

column 3 = temperature

then one plot(column 1, column 3)

then one want to concatenate column 1 and column 2 in the x axis of the plot.

[Star Strider]

Try this:

x1 = datetime('now', 'TimeZone','America/New_York', 'Format','HH:mm') + hours(1:10);
x2 = datetime(x1, 'TimeZone','America/Los_Angeles', 'Format','HH:00');
y = rand(1,10);

figure
plot(x1, y)
xt = get(gca, 'XTick');
x2tklbl = sprintfc('%s', x2);
text(xt(1:end-1), (min(ylim)-0.05*diff(ylim))*ones(size(xt(1:end-1))), x2tklbl, 'HorizontalAlignment','center', 'VerticalAlignment','top', 'FontSize',9)

That is my best effort. You will likely need to adapt it to your spreadsheet times, with respect to format and other details.

[alpedhuez]

Thank you. This is not an easy problem. I will work on it.

[Star Strider]

As always, my pleasure!

I quite definitely agree that it is not an easy problem!

[alpedhuez]

Thnak you.