Plotting data with timestamps
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Hi,
I have some data from a sensor and corresponding timestamps. How do I plot this data? (x axis - timestamps, y-axis - data) plot function gives empty figures. Probably because timestamps cannot be put in a linear scale. I tried semilogx - this also gives empty figures.
How do I do this?
Thanks in advance
采纳的回答
Convert from whatever format the timestamps are in to a Matlab representation of dates...with R2014 up, there's the datetime class; prior to that use datenum. See <datetime> for current versions; plot is datetime -aware.
7 个评论
Walter Roberson
2016-11-28
datetime() offers a 'ConvertFrom', 'posixtime'. The numbers you showed in the image convert into dates today if you divide them by 1000 before doing the conversion.
lexi11
2016-11-28
lexi11
2016-11-30
Munshi Mahbubur Rahman
2018-10-30
what have you guys used for the dateType argument? My data is in unix timestamp
dpb
2018-10-30
Well, Unix timestamp is in seconds from Jan 1, 1970 but your data are too big for that; they seem to have been encoded as integer values to the millisecond resolution...
>> t=datetime(1489337264031/1000,'ConvertFrom','posixtime')
t =
datetime
12-Mar-2017 16:47:44
>> t.Format=[t.Format '.SSS']
t =
datetime
12-Mar-2017 16:47:44.031
>>
You'll notice the fractional seconds match up with the last significant digits in the original number.
Peter Perkins
2018-10-31
In recent versions of MATLAB, you can also convert directly from ms since 1970:
>> datetime(1489337264031,'ConvertFrom','EpochTime','TicksPerSecond',1000,'Format','dd-MMM-yyyy HH:mm:ss.SSS')
ans =
datetime
12-Mar-2017 16:47:44.031
The 'Epoch' parameter defaults to 1-Jan-1970, which is convenient if you have posix timestamps.
dpb
2018-10-31
Thanks for making aware of that, Peter...
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