# How can determine the sampling frequency from a time series data?

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Lisa Justin on 21 Aug 2012
i need the sampling frequenccy of a give time series data. it is a 1x31225 time data if i choose any two point say x(:,1) and x(:,2)
1/x(:,2)-x(:,1) does not give a likely sampling frequency, it gives about 0.2144 for instance. please help out
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### Accepted Answer

Star Strider on 21 Aug 2012
Edited: Star Strider on 21 Aug 2012
All may not be lost. When I searched for information on .sif files, I came up with a number of different definitions, including Andor Scan Information File (there are at least two TMW File Exchange entries for those), and Cytoscape Simple Interaction Format. (They are also Windows Setup Information Files, but those likely aren't the ones you are interested in.)
What generated your .sif file, and what does it contain? How many rows and columns should it have? If it is supposed to be a matrix rather than a vector, it may be possible to get the time data (if there is a time vector in the matrix) by doing reshape on it.
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### More Answers (1)

Azzi Abdelmalek on 21 Aug 2012
if x(:,1) is time and x(:,2) is your signal
then, if the sample frequency is constante
f=1/((x(2,1)-x(1,1))
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Lisa Justin on 21 Aug 2012
Edited: Lisa Justin on 22 Oct 2012
i guess it was lost from conversion from a SIF file. but i have only the converted file, any ideas
Azzi Abdelmalek on 19 Oct 2012
Without a vector time, we can't find your sample frequency. I can't guess what happens to your file.

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