How to display XTicks from the command line?

INTRO: Hi I plot arbitrary data against date ticks for hours of the day as below:

%Get traffic count data
load count.dat
% Create arrays for an arbitrary date, here April 18, 1995
n = length(count);
year = 1990 * ones(1,n);
month = 4 * ones(1,n);
day = 18 * ones(1,n);
% Create arrays for each of 24 hours;
hour = 1:n;
minutes = zeros(1,n);
% Get the datenums for the data (only hours change)
xdate = datenum(year,month,day,hour,minutes,minutes);
% Plot the traffic data against datenums
plot(xdate,count)
% Update the graph's x-axis with date ticks
datetick('x','HHPM')

GOAL: I want to display the XTicks and modified the following lines:

h=subplot(1,1,1);
plot(xdate,count);

set(h,'XTick',xdate)
datetick(h,'x','HH','keepticks')

QUESTION: Why do I need to use subplot to display the XTick? I have also the version suggested by Walter:

h = plot(xdate,count);
haxis = ancestor(h, 'axes');
set(haxis, 'XTick', xdate);
datetick(haxis, 'x', 'HHPM')

but I still obtain the following error:

Error using set
Conversion to double from cell is not possible.

I wonder if someone could help me to correct these command lines and avoid the use of subplot.

Thank you in advance for your help

Emerson

Answer 1

[Walter Roberson]

Plots do not have ticks, axes have ticks.

h = plot(xdate,count);
haxis = ancestor(h, 'axes');
set(haxis, 'XTick', xdate);
datetick(haxis, 'x', 'HHPM')

[Emerson De Souza]

Hi Walter, thanks for the instructions. I followed your suggestion, but I still obtain the following error:

Error using set
Conversion to double from cell is not possible.

Do you know how to solve this?

Thanks

[Walter Roberson]

Is your count a 2D array instead of a vector? If so then you need to change to

haxis = ancestor(h(1), 'axes');

which will also work for the case where count is a vector.

[Emerson De Souza]

Thank you Walter,

the line above fixes the problem.