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Peter Perkins


MathWorks

993 total contributions since 2011

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Answered
How to convert time to a number?
>> d = duration('17:15','Format','mm:ss') d = duration 17:15 >> d.Format = 'm' d = duration 17.25 min

2 days ago | 0

Answered
Is there a list of datastore SelectedFormats?
Somewhat buried in the tabularTextDatastore doc: "You can use the same conversion specifiers that the textscan function accepts"...

2 months ago | 0

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Answered
Problems with empty cell in a large matrix
You have a fixed-width file, and readtable needs to be told how it's organized, using fixedWidthImportOptions: >> opts = fixedW...

2 months ago | 1

| accepted

Answered
How to subset a table with character elements
Blue, I'm a little late to the party, but at least for those data, what you really ought to do is use a categorical for t.type. ...

2 months ago | 0

Answered
Tables and files in matlab
Does this not do what you want? >> t = readtable('Um7V.txt','Delimiter',';','ReadVariableNames',false); >> head(t) ans = 8...

3 months ago | 1

Answered
How do I plot a datetime vs data within a cell array?
You almost certyainly do not want to store your data like that. For one thing, cell arrays are designed for complete generality,...

4 months ago | 0

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Answered
Pairwise difference of datetime vectors (i.e. pdist for time data)
pdist is probably much more than you actually need, assuming that by "distance" you mean a simple subtraction. pdist is designed...

4 months ago | 1

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Answered
Convert JSON datetime-wire-format
This appears to be some kind of weird mix of a text and a numeric representation that includes milliseconds since 1-Jan-1970 UTC...

4 months ago | 0

Answered
Devide a table in several tables by criteria
You can do this in several ways, but honestly the most straight-forward is to write a loop, as shown below. The real question is...

4 months ago | 1

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Answered
Two "Time" colunm in a time table
Correct, there is only one vector of times to label the rows of a timetable. But that's not to say you can't put both vectors in...

4 months ago | 0

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Answered
split timetables into multiple hourly timetables and save as separate .mat files
You can do this in several ways, but honestly the most straight-forward is to write a loop, as shown below. The real question is...

4 months ago | 0

Answered
Separating tables in tables after importing
Walter is correct, it's probaby not a good idea to split the table into separate workspace variables. And as he also says, it's ...

4 months ago | 0

Answered
time formate changes while exporting table as excel
S.M., are you quite sure this is not simply a formatting issue in the spreadsheet? When I run this code in a recent version of M...

4 months ago | 1

Answered
How to fix the missing patches that turn into NAT?
It's possible that what's happening is that your timestamps are stored in the spreadsheet file as text, not as dates, and that s...

4 months ago | 0

Answered
Bar plot using multiple table variables?
It's not completely clear what you are asking for, but my guess is that you want bar, with the 'stacked' input, and t{2:7,2:4} a...

4 months ago | 0

Answered
how to identify unique columns, based on the first two rows, make an average of the uniques columns and remove the duplicate columns?
You may have a reason for wanting row-oriented data, but I'm gonna suggest that you transpose your data, create a table, and use...

4 months ago | 0

Answered
How to pivot the table
At first glance, this seems like you could be using the unstack function, and it may be that you can. But you are a bit out of m...

4 months ago | 1

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Answered
Plotting two different dimensions time series data on the same x-axis
>> x1 = rand(1,6); t1 = datetime(2019,6,12,1:6,0,0,0); >> x2 = rand(1,24); t2 = datetime(2019,6,12,1,(0:23)*15,0); >> plot(t1,...

4 months ago | 0

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Answered
Creating a for loop to see if date exists
Also, it may be that you need to "find that date and find the position of where it is located" because you'll then use that loca...

4 months ago | 0

Answered
How to import text to timetable with ntsf timestamp
"it only accepts a number formated as uint64" NTFS timestamps are defined as 64bit numbers. Anything smaller than that and you ...

4 months ago | 0

Answered
How to ensure my times will follow daylight savings?
The answer is don't use datenums. They do not support time zomes at all. Use datetimes. If you set the TimeZone property on you...

4 months ago | 0

Answered
Round down to a chosen hour-min-sec time at a date
Since you're working in liear time (preserving dates) and no in circular time (caring only about time of day), I would think dis...

4 months ago | 0

Answered
Plotting date time Hear rate and Stress in the same plot and/or in different plots
After a bit of cleaning up, I get this timetable: >> TT = readtimetable('SHS.csv'); >> TT.Time.Format = "dd-MMM-yyyy"; >> TT....

4 months ago | 1

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Answered
How to add datetime from seconds?
That's not the error that I get, but it's possible that you are using an older version with different error handling. In any ca...

4 months ago | 1

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Answered
Split timetable using retime
You are using datetimes, which is a linear time line. It sounds like you want "time of day", which is a circular time line. I ca...

4 months ago | 0

Answered
How to import text to timetable with ntsf timestamp
In recent versions (since R2018a? or thereabouts): >> help datetime [snip] D = datetime(X,'ConvertFrom',TYPE) converts the nu...

4 months ago | 0

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Answered
How to identify entries for a time frame?
The data in your example are VERY sparse, and it's hard to know if that's typical or not. One very simple way to do what you wa...

5 months ago | 0

Answered
How can I extract data from a table and put it into a new one?
With no example, it's hard to understand what you have and what you want to end up with, but your description sounds very much l...

5 months ago | 0

Answered
extract data for a specified date and time period
Abhishek, you have not made clear what problem you are actually running into. One of the problems is that every 400 rows or so, ...

5 months ago | 2

Answered
extract column name of table with Nan column
Using {:,:} to convert the entire table to a homogeneous array is perhaps one way to do this, but scales badly very quickly as t...

5 months ago | 0

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