Hot to take the first data values out and then plot all of data

So each sample I take has 406 csv's. And I would like to leave the first six values out of the sample and then plot, just without those first 6 values. New to matlab. Any ideas?

Thanks

Answer 1

[Star Strider]

There are at least three ways to deal with that, depending on the function you’re using to read your .csv files.

1. Define the range of values to read in xlsread and csvread (see the respective function documentation),
2. Define 'HeaderLines',6 in textscan,
3. Read in everything and then delete the first 6 rows, regardless of the function you use to import them.

[m j]

Thanks I looked into all of them and it will remove the unwanted values. But how would I go about always removing the first 6 numbers of a 406 sample in a ....say 40000 data file .So every 406 values, I need to remove those first 6 until the end of 40000 or any size?

[Image Analyst]

Attach your csv file and say what you want to ignore. I can't tell if you don't want the first 6 rows (lines) or first 6 columns. When you ambiguously say "each sample I take has 406 csv's" do you mean you have 406 variables in a single CSV file, OR do you mean that you have 406 CSV files with some other number of rows and columns in it?

[m j]

I want to remove the first 6 values(which is a timestamp) and keep the next 400 values and then remove the next 6 values and keep the next 400, etc....Also if you notice there are blank spaces, after the last blank space there is a timestamp. And then be able to plot them all on matlab

[Star Strider]

I didn’t see any blank spaces, but then that’s a huge file.

This seems to do what you want:

fidi = fopen('mike haag recording.txt','rt');
d = textscan(fidi, ['%*f%*f%*f%*f%*f%*f' repmat('%f', 1, 400)], 'CollectOutput',1, 'Delimiter',',');
Data = cell2mat(d);

x = 1:size(Data,2);
figure(1)
plot(x, Data)
grid

The plot:

I saved your data to that specific file because everyone names their file similarly and this keeps them separate in my computer.

[m j]

perfect but I am having trouble figuring out this line.

'%*f%*f%*f%*f%*f%*f' repmat('%f', 1, 400)] so you create a string of 6 floats and then call repmat and have the first 6 floats be transferred into the 6 '%*f%*f%*f%*f%*f%*f' string?

[Star Strider]

Thank you.

The entire format descriptor is:

['%*f%*f%*f%*f%*f%*f' repmat('%f', 1, 400)]

In MATLAB, the square brackets when applied to strings act as a concatenation operator, here forming one string of all the elements within the brackets. The first six fields are ‘%*f’, with the asterisk telling MATLAB to ignore each of those fields. The repmat call avoids my having to type ‘%f’ 400 times to read in the 400 following values. (I could have use a repmat call for the first six fields as well, but considered that to be sort of ‘overkill’.)

Answer 2

[Walter Roberson]

YourData([1:406:end, 2:406:end, 3:406:end, 4:406:end, 5:406:end, 6:406:end], :) = [];