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# Peter Perkins

### MathWorks

Last seen: 3 months ago Active since 2011

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How to output a for to a 10x27 table (for loop keeps overwriting the variable)
Marshall, the advice to try to vectorize is good advice, but if that's not possible, you might try something like at this: heig...

3 months ago | 0

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Customized datetime format within table
Vic, I think you want synchronize. tt1 = timetable([1;2;3;4;5],RowTimes=datetime(2023,1:5,1)) tt2 = timetable([6;7;8;9;10],Row...

3 months ago | 0

Line of Best Fit for a time series plot
There are a bunch of things you might mean by this, but here's one thing you might do. % set up random data Time = datetime(19...

3 months ago | 0

Direct calculations on tables - elementwise mean of n-tables
If I understand your situation correctly, data{1:end} is a "comma-separated list" of tables, and so mean(data{1:end}) in effect ...

3 months ago | 0

How can I compress a table
Here's another possibility, using rowfun, that returns a table containing tables, which maybe is easier to use than what you ask...

3 months ago | 1

Help with graphing table into line graph
This spreadsheet is kind of messed up, and I will let you figure out how best to read it in. Given that, it seems like stackedpl...

3 months ago | 0

How to finding GAPS in satellite access times.
There are ways to do this without loops, but the most straight-forward way (assuming the data are sorted by start time) is brute...

3 months ago | 0

Index and select rows from table
"I need to split the original data based on the categories of col5." You probably do not want/need to do that. Take a look at t...

3 months ago | 0

how can I get a list of the countries used by the mapping toolbox as a cell array?
Stephen seems to have answered your question, but also, you will find categorical useful for cleaning your data: countryList = ...

3 months ago | 0

I have a problem with my script. I would like to extract pH data from the coast of Cameroon or the Gulf of Guinea. Can I have some ideas on what is bugging my script and a cor
Using datenums is no longer recomended. t1=double(ncread([PathName,FileName],'TIME')); ... t(i)=datenum(1900,1,1,0,0,0...

3 months ago | 0

Change of frequency content after using the retime function
Julius, I'm definitely not any kind of signal processing expert, but I think what you want is resample, from the Signal Processi...

4 months ago | 0

Sampling and Filtering Table Data
Presumably you would have a timetable. If you have the Signal Processing Tbx, you should look at resample.

4 months ago | 0

How can I align deterministic signals?
Some of what SS shows might be easier with timetables: for i = 1:4 signal = load("ew_data"+i+".mat"); signal = signal.ans;...

4 months ago | 1

My exported EDF file is up to 100 times bigger than my imported EDF file
I don't know much about EDF, and there's no fil attached, but my guess is that the culprit is Voltage_V = vertcat(Data.EEG{:});...

4 months ago | 0

Plotting bar graph from website
Marcus, it looks to me like what you have is a year-by-month array. As others have said, those bars are mightily thin. Have you...

4 months ago | 0

Trouble with date conversion
Worth saying that if the file was a spreadsheet and contained things like 20230101 as numeric values, there's a conversion for t...

4 months ago | 1

How to get columns as 'struct' in timetable
Ludo, I'm not 100% sure I follow your question, but lemme take a shot. As Stephen shows, a variable in a table can be a struct ...

4 months ago | 1

How to get columns as 'struct' in timetable
For the record, you are correct that timetable is the recommended way to work with timestamped data, but there are no plans to a...

4 months ago | 1

Plotting double vs datetime (DD-MM-YY), only the year is used from the datetime
Paul, in addition to what Walter said, those mat files each contain a bunch of 23041xN variables. Likely you would benefit from ...

4 months ago | 0

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How to update leap seconds
James, there's no way for customers to update MATLAB with new leap seconds. The IERS data is built into a binary file. The last...

6 months ago | 0

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How to find differences between 2 large tables that have a mix of string and numbers?
I thnk looping over every row in the tables will not be very performant. I would think this will do better: matches = false(siz...

8 months ago | 0

Importing data from Delsys Trigno software .csv
If you really have a csv, if it really has variable names spread over two lines, user NumHeaderLines to tell readtable to skip e...

8 months ago | 0

How to use groupsummary to group by hour-of-year
Is this really "hour of year", a value that runs from 0 to 8784? In the same way that day of year is just dt = datetime(2023,7,...

8 months ago | 0

mean of all these variables over latitude x longitude x time that is (5 x 5 x 2)
It's very likely that you should be using a timetable. You have "eight variables loaded with data (latitude,longitude,time,mont...

8 months ago | 0

How to calculate the date 0.25 years after the date of January 15, 2020
This is a long thread. I hope the following will clarify a couple things. The years function is not really intended for precise...

8 months ago | 0

seasonal mean for each year based on the sample code

8 months ago | 0

Duplicating categorical array to floating point value for perfcurve function
The short answer is that you can call double on a categorical array to get the category numbers as a numeric array. But that may...

8 months ago | 0

years in fourth dimension is not printing properly

8 months ago | 0