How to flip a signal ?

Hi all,

I have an acceleration signal during human walking (walk forward, turn around, walk back).

The attached is the 24x1 cell containing arrays of dimensions 100x 1 and each of these respresent acceleration signal between certain indices in the signal. Each array is plotted over the figure below.

When the subjects turns around, it seems the signal is flipped around resulting in a half of the arrays being a negative mirror image of the remaining half of the arrays.

This is more visible if a plot first 12 arrays and second 12 arrays on seperate figures:

%Load data
load('P_acc_y_cycle')
%Plot each array
figure
hold on
    for i = 1:12
        plot(P_acc_y_cycle{i},'r');
    end      
figure
    hold on
    for i = 13:24
        plot(P_acc_y_cycle{i},'r') ;
    end  

How can I flip the first part (first 12 arrays) so it resembles the second part?

Answer 1

[Mathieu NOE]

hello

you simply apply a negative gain = -1 to your data you want vertical flipped

%Load data
load('P_acc_y_cycle')
%Plot each array
figure
hold on
    for i = 1:12
        plot(-P_acc_y_cycle{i},'r'); % here negative gain =  -1 
    end      
    for i = 13:24
        plot(P_acc_y_cycle{i},'b') ;
    end     

Answer 2

[David Hill]

plot(abs(P_acc_y_cycle{i}-10)-10,'r') ;