Insert Date Column Based off Known Start and Stop Time

2017 2 7
2 个回答
更新时间：2017 2 9
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Hello,
I have processed data that covers a 5 month period and have 3 columns of data that give me the x, y, and z rotation of an object. The data is divided by data points and not by time. I know the start and stop time for the data logging. What is the best way to create a date field that I can fill in the start and end time? Ideally I'd like to plot these values with known date values instead of just the data point value on the x-axis.

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the cyclist
the cyclist 2017-2-7
It would be a lot easier to understand your question if you posted a small (but representative) example of the input/output you expect.
Don't just describe it. Post actual code, or upload a MAT file.

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回答（2 个）

Peter Perkins
Peter Perkins 2017-2-8

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It sounds like maybe you want a table that contains two datetime variables as well as x, y, and z, but as the cyclist says, you're gonna have to provide more details.
Daniel Devereaux
Daniel Devereaux 2017-2-8

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Hi. I've attached a MAT file that covers 3 hours of data. The unit collects data points at 100hz for 10min every 3 hrs. So it runs for 10 mins after the following start time with each data point representing .01 of a second.
Start time: 6:08:00 PM UTC 2016-05-22
How would I be able to plot these three columns of data (x,y,z) against time referenced to this start time in that increment?

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Peter Perkins
Peter Perkins 2017-2-9
Here's some code that works in R2016b:
>> t0 = datetime('6:08:00 PM UTC 2016-05-22','InputFormat','hh:mm:ss a ''UTC'' yyyy-MM-dd');
>> t0.Format = 'yyyy-MM-dd HH:mm:ss.SSS';
>> d = (minutes(0):milliseconds(10):minutes(10))';
>> t = t0 + d;
>> xyz = cumsum(randn(length(t),3));
>> tt = array2timetable(xyz,'RowTimes',t,'VariableNames',{'x' 'y' 'z'})
tt =
Time x y z
_______________________ ______ ________ ________
2016-05-22 18:08:00.000 0.2992 -0.95717 0.01993
2016-05-22 18:08:00.010 1.7475 -1.054 -0.52164
2016-05-22 18:08:00.020 2.2103 -0.2601 -0.66848
2016-05-22 18:08:00.030 2.7189 0.69421 -0.41496
2016-05-22 18:08:00.040 2.381 0.28662 -1.789
2016-05-22 18:08:00.050 4.5419 0.76694 -0.78308
2016-05-22 18:08:00.060 3.748 1.9123 -2.2305
2016-05-22 18:08:00.070 2.7249 0.9289 -3.7441
2016-05-22 18:08:00.080 2.4665 2.068 -3.9346
2016-05-22 18:08:00.090 1.3154 1.2933 -4.4244
[snip]
Plot all three vars on one axis:
plot(tt.Time,tt.Variables)
legend(tt.Properties.VariableNames)
Plot on separate axes (using ttplot from the File Exchange):
ttplot(tt)
Both can also be done prior to R2016b, using a table, not a timetable.
Hard to know how you want to handle those 2hr 50min gaps, the above only plots one segment.

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