pre-set axis limit to datetime

Hi:

I have a figure and I want to set the x-axis to 'datetime' type before add any plot there, below is the code:

figure
ax=gca;
ax.XLim=[datetime('now'),datetime('now')+day(1)]

Matlab reported error like below:

Value must be a 1x2 vector of numeric type in which the second element is greater than the first element or is Inf.

however, the code below works:

figure
ax=gca;
ax.XLim=[1,2]

and the code below works:

ax=gca;
ax.XLim=[1,2]
figure
plot([datetime('now'),datetime('now')+day(1)],[1,1])

so, it seems like the Matlab do not accept set the x-axis to datetime if no 'datetime' type plot added to the figure.

is there anyway can address this issue?

Thanks!

Yu

Answer 1

[Seth Furman]

The axis ruler can be set directly to a DatetimeRuler.

https://www.mathworks.com/help/matlab/ref/matlab.graphics.axis.decorator.datetimeruler-properties.html

ax = axes;
ax.XAxis = matlab.graphics.axis.decorator.DatetimeRuler;
ax.XLim = [datetime(2020,1,1) datetime(2020,1,2)];

[Yu Li]

Hi:

Your sample code works fine, the problem is that, if I set the time zone for the datetime, Matlab report error. Below is the sample code:

figure
ax=gca;
ax.XAxis = matlab.graphics.axis.decorator.DatetimeRuler;
ax.XLim = [datetime('now','TimeZone', 'America/New_York'),datetime('now','TimeZone', 'America/New_York')+day(2)]

do you have any further suggestions?

Thanks!

[Seth Furman]

Good catch. In this case, it would be simpler to call plot with dummy data and then clear the axes.

https://www.mathworks.com/help/matlab/ref/cla.html

xLimits = [datetime('now','TimeZone', 'America/New_York') datetime('now','TimeZone', 'America/New_York')+day(2)];
yLimits = [0 1];
ax = gca;
plot(ax, xLimits, yLimits);

cla(ax); % clear axes
ax.XLim = xLimits;
ax.YLim = yLimits;

[VBBV]

figure
ax=gca;
ax.XAxis = matlab.graphics.axis.decorator.DatetimeRuler;
plot(ax,[datetime('now','TimeZone', 'America/New_York'),datetime('now','TimeZone', 'America/New_York')+day(2)])

cla(ax)
ax.XLim = [datetime('now','TimeZone', 'America/New_York'),datetime('now','TimeZone', 'America/New_York')+day(2)]

Value must be a 1x2 vector of numeric type in which the second element is greater than the first element or is Inf.

ax.YLim = [ 0 1]

if cla(ax) is used as told, it still produces the same error

[Steven Lord]

If you don't want a visible line on your axes you could plot using NaN as the Y data.

N = datetime('now','TimeZone', 'America/New_York');
plot(N, NaN);
xlim([N, N+days(2)])
ylim([0 1]);