Script for CSV processing

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Antonio Jayena
Antonio Jayena 2015-3-23
评论： dpb 2015-3-23
Hi friends.
First of all I apologize for my bad English.
I tell you my problem. I was working with an osciloscope and I take around 500 measures (Voltage/Time) in CSV files. The signal is a pulse train with only the 1% of the period crossing the zero.I want to measure with matlab, for each csv, which is the value of x axis (time) for exactly 25 pulses of the whole train.
Doing this with cursors is a very hard work. I'm trying to build a Script. My main idea (because of the small time that the signal cross the zero) is to make a FOR loop, with a IF loop inside that, when Y axis have crossed the zero 25 times, the script catchs the value of the X axis in a new variable. This operation, with the bucle, for all the CSV files.
This is my idea, but Im new in Matlab and is costing me a lot.
Anyone can help me? Thank you very much.
  1 个评论
Antonio Jayena
Antonio Jayena 2015-3-23
Im trying to go in other way, but I'm faling in the sintax
j=1
i=1
for i=1:30
s=csvread('scope_0_1.csv',2,0);
if (r2==0) % when signal cross zero
j=j+1
else
if (j==25) % finding the 25th zero crossing
disp('s');
j=0;
i=i+1;
end
Any help plis?

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回答（2 个）

dpb
dpb 2015-3-23
s=csvread('yourfile.csv'); % read the signal
ix=find([0 diff(s>0)==1,25); % locate first 25 zero crossings
The above works by turning the input signal into a 0/1 pulse train, then looks for the positive crossing locations (where the 0 turns to 1 is a +1 difference).
The ix index vector is the position in the original vector of those crossings, specifically it will be the index of the first positive location after the zero-crossing.
Antonio Jayena
Antonio Jayena 2015-3-23
Im trying to go in other way, but I'm faling in the sintax
j=1
i=1
for i=1:30
s=csvread('scope_0_1.csv',2,0);
if (r2==0) % when signal cross zero
j=j+1
else
if (j==25) % finding the 25th zero crossing
disp('s');
j=0;
i=i+1;
end
Any help plis?
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Antonio Jayena
Antonio Jayena 2015-3-23
I´m trying but I get errors.
Error using horzcat
Dimensions of matrices being concatenated are not
consistent.
Error in Matlab (line 2)
ix=find([0 diff(s>0)==1,25]);
Mi CSV has 2 colums (voltage and time)...is here my error? I make a loop because I have a lot of CSV files, and Im triying to get the value of each one printing in each iteration with
disp('s')
Thank you for your effort.
dpb
dpb 2015-3-23
OK, I presumed a row vector in s; for a Nx2 array then for the voltage column it would be
ix=find([0; diff(s(:,1)>0)==1,25]);
again assuming the data array is s; obviously use whatever you use in your script.
For processing multiple files, you might look at the File Exchange function filefun that applies a function "automagically" to each function. It's at <Apply a function to files>

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