Calcuating equally-spaced sums from unevenly-spaced time-series data

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dormant
dormant 2022-8-4
编辑： Cris LaPierre 2022-8-5
I need to create an equally-spaced vector of values which are the sums from a vector of unequally-spaced values.
More specifically, I have a file which has the number of bytes received and the time they were received. There are usually more than a million lines in the file. I want to plot the data rate every five minutes. To make things more difficult, the timestamps might not always be in order.
This is my code so far. I could write a loop to populate kbps, but is there an easier way to do it?
D = textscan( fid, '%f %d\n' );
datim = D{1}; % Posix timestamp
bytes = D{2}; % Number of bytes
t1 = dateshift(datetime(min(datim), 'ConvertFrom', 'posixtime'), 'start','day');
t2 = dateshift(datetime(max(datim), 'ConvertFrom', 'posixtime'), 'end','day');
t = t1:minutes(5):t2;
kbps = nan( size(t) );
And here are the variables:

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Cris LaPierre
Cris LaPierre 2022-8-4
编辑：Cris LaPierre 2022-8-5
I would put your datetime and bytes into a table (consider cell2table). Convert your times to datetime, and then use sortrows to place them in order (if desired).
With the data in a table, you can use groupsummary to compute the number of datapoints in bins you specify, where groupbins is the bin edges.
G = groupsummary(T,groupvars,groupbins)
You could use the data you already have captured in t for your edges:
Consider sharing your data and we can test actual code. You can attach it using the paperclip icon.
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dormant
dormant 2022-8-5
Here is my working code. Many, many, many thanks.
D = readtable( fileSniff );
D = sortrows(D,1);
D.Var1 = datetime( D.Var1, 'ConvertFrom', 'posixtime' );
tBeg = dateshift(D.Var1(1), 'start', 'hour');
tEnd = dateshift(D.Var1(end), 'end', 'hour');
T = tBeg:minutes(5):tEnd;
G = groupsummary(D,'Var1',T,'sum');

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