Trouble using findpeaks function

The attached data is a sinusodial wave. I want to find how many peaks are in this graph. In matlab, I click on the file and import thata data from both columns. I get the following error:

Error using findpeaks

Expected Y to be one of these types:

double, single

Instead its type was table.

Error in findpeaks>parse_inputs (line 199)

validateattributes(Yin,{'double','single'},{'nonempty','real','vector'},...

Error in findpeaks (line 135)

= parse_inputs(isInMATLAB,Yin,varargin{:});

So importing the data that way makes it a table.

Ok so i make a variable for each column and turned them into a 5464x1 matrix.

Im not sure what to do next in order to analyze the peaks. ANy help?

Answer 1

[Star Strider]

I have no idea how you are importing them. The findpeaks function wants real vector data.

Try something like this —

T1 = readtable('run 4 vac to air volt.csv', 'VariableNamingRule','preserve')

T1 = 5464×2 table
    Voltage, Ch A (V) Run #4    Voltage, Ch B (V) Run #4
    ________________________    ________________________

             -0.218                      -9.412         
             -0.218                      -9.413         
             -0.218                      -9.413         
             -0.218                      -9.412         
             -0.218                      -9.412         
             -0.218                      -9.413         
             -0.218                      -9.413         
             -0.218                      -9.413         
             -0.218                      -9.412         
             -0.218                      -9.413         
             -0.219                      -9.413         
             -0.219                      -9.413         
             -0.219                      -9.413         
             -0.219                      -9.413         
             -0.218                      -9.412         
             -0.219                      -9.413         

ChA = T1{:,1};
ChB = T1{:,2};

[pksA,locsA] = findpeaks(ChA, 'MinPeakProminence',0.01);
[pksB,locsB] = findpeaks(ChB, 'MinPeakProminence',0.01);

figure
subplot(2,1,1)
plot(ChA)
hold on
plot(locsA,pksA, '+r')
hold off
hold on
hold off
subplot(2,1,2)
plot(ChB)
hold on
plot(locsB,pksB, '+r')
hold off

Note the use of curly braces {} to index into the table array.

Make appropriate changes to get the results you want.

.