I've been trying to implement a set of loops and conditionals to carry out the following operation: if sample(i+1)-sample(i) > value if this statement is true FOR AT LEAST 5 consecutive samples then fill another pre-allocated vector with the sample from point where true up until the point where not true. Thanks for the help.

Loops and conditional statement problem

madhan ravi 2018-7-16

Can you show the example ?

Tom Shemeld 2018-7-16

Var1 is a 1D variable with data that is N samples long.

Allocate vector full of zeros to be filled: => Var2 = zeros(length(Var1),1);

Initiate loop (my coding is quite poor):

for i=1:length(Var1) if Var1(i+1)-Var1(i)>10 _

then if statement above is true for at least 5 consecutive samples. Take the sample where this condition is first true and increment until Var1(i+1) - Var(i) < 10 and place in Var2.

J. Alex Lee 2018-7-23

在 MATLAB Online 中打开

A simple way to get as far as flagging positions where your condition is met without looping:

 dVar1 = diff(Var1) % find differences between successive entries
 flag = dVar1>10 % flag the positions where the difference is greater than 10

This gives you a logical array of length N-1, and now you have the problem of finding consecutive true's of length longer than 5...i found this interesting answer elsewhere: https://www.mathworks.com/matlabcentral/answers/366126-how-many-consecutive-ones

Matt C 2018-7-25

在 MATLAB Online 中打开

To build off the answer above, given the flag variable of logicals, this pseudo-code below could potentially solve your problem for actually copying over the parts of the vector that satisfy the condition.

       % Track if the last seen element was zero.
        lastSeenWasZero = true;
        % Track how many consecutives ones have been seen.
        oneCounter = 0;  
        for i = 1:length(flag)
           % If last seen element was zero and current element is one, then save the beginning index of the sequence
           if lastSeenWasZero && flag(i)
               startSubsequence = i
           end
           % If the current element is one, then increment a counter of how many consecutive ones have been seen.
           if flag(i)
               lastSeenWasZero = false;
               oneCounter = oneCounter + 1
           end
           % If element is zero, check if at least last 5 elements were ones. If so, then copy the elements which satisfied the condition over from one array to another.
           if ~flag(i)
               lastSeenWasZero = true;
               if oneCounter >= 5
                   Var2(startSubsequence:startSubsequence+oneCounter) = Var1(startSubsequence:startSubsequence+oneCounter)
               end
               oneCounter = 0
            end
         end
         %After hitting the end of the flags array, need to check if there were many ones all at the end of the vector.
         if oneCounter >= 5
            Var2(startSubsequence:startSubsequence+oneCounter) = Var1(startSubsequence:startSubsequence+oneCounter)
         end

KALYAN ACHARJYA 2018-7-25

The question seems very easy, more clarification needed.

Loops and conditional statement problem

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