# How to plot datetime array?

72 vues (au cours des 30 derniers jours)
Asher Zaidi le 18 Juin 2018
Commenté : Bucks Lin le 14 Avr 2022
I would like to plot a vector, r, as a function of time. The two vectors I have are:
r'
1.0e+03 *
0.0179
0.0180
0.0184
0.0184
0.0189
0.0189
0.0189
0.0189
0.0190
0.0190
ds =
10×1 datetime array
02-Feb-2018 11:08:11
02-Feb-2018 12:08:13
02-Feb-2018 01:08:14
02-Feb-2018 02:08:15
02-Feb-2018 03:08:17
02-Feb-2018 04:08:18
02-Feb-2018 05:08:20
02-Feb-2018 06:08:21
02-Feb-2018 07:08:23
02-Feb-2018 08:08:24
However, when I try to plot them:
plot(datenum(ds), r, '-o')
datetick('x', 'dd-mmm-yyyy HH:MM:SS')
I get this graph (see attached). I would like for each point to have a corresponding time and date on the x-axis, if it is possible.
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### Réponse acceptée

Walter Roberson le 18 Juin 2018
plot(ds, rs, '-o')
From R2016b onward, you can use datetime objects as the x or y axes. (Exact release varies a bit with variety of graph being plotted.)
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Walter Roberson le 19 Juin 2018
You could get that if you were trying to do a datetime plot on top of an existing numeric axes.
If you are trying to draw on top of an existing axes, then you might have "hold on" in effect, and that might have affected the xtick values that the axes thought should be used.
When I use your commands together with
ds = datetime({'02-Feb-2018 11:08:11'
'02-Feb-2018 12:08:13'
'02-Feb-2018 01:08:14'
'02-Feb-2018 02:08:15'
'02-Feb-2018 03:08:17'
'02-Feb-2018 04:08:18'
'02-Feb-2018 05:08:20'
'02-Feb-2018 06:08:21'
'02-Feb-2018 07:08:23'
'02-Feb-2018 08:08:24'});
r = 1e3 * [ 0.0179
0.0180
0.0184
0.0184
0.0189
0.0189
0.0189
0.0189
0.0190
0.0190];
then xtick creates labels for every 3 hours.
Asher Zaidi le 20 Juin 2018
I see, thank you!

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### Plus de réponses (1)

Aron Magesh le 22 Mai 2020
If you have used hold on function, make sure to use the hold off as well to avoid this error.
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Bucks Lin le 14 Avr 2022
wow!
thanks Aron!! your tips save my day.

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