accepting values into an array, then accepting new values by shifting left
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Michael Scott
on 10 Feb 2018
Commented: Michael Scott
on 11 Apr 2018
I am calling a function in a different m file. I want this function to write newValues into an array. After 7 entries, the newValues need to be added to the end of the array and then shifted left in order to keep the values in order. Example: values accepted in the array are [1 2 3 4 5 6 7]. The new value is 8 which makes the array have values [2 3 4 5 6 7 8]. This is what I have so far....
function arrayWithLatestValues = fn_updateArray(newValue)
persistent A;
A = [A(2:end) newValue];
arrayWithLatestValues = A;
end
this is my output im getting:
0 0 0 0 0 0 0
0 0 0 0 0 0 0
0 0 0 0 0 0 0
0 0 0 0 0 0 0
0 0 0 0 0 0 0
0 0 0 0 0 0 0
0 0 0 0 0 0 0
0 0 0 0 0 0 0
0 0 0 0 0 0 0
0 0 0 0 0 0 0
0 0 0 0 0 0 0
0 0 0 0 0 0 0
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Accepted Answer
possibility
on 10 Feb 2018
Edited: possibility
on 10 Feb 2018
I'm guessing it is because of the persistent statement. Quote from the statement explanation:
" If the persistent variable does not exist the first time you issue the persistent statement, it will be initialized to the empty matrix."
If you have the vector as an input to the function, I believe the problem will be solved.
function arrayWithLatestValues = fn_updateArray(newValue,A)
A = [A(2:end) newValue];
arrayWithLatestValues = A;
end
More Answers (1)
Stephen23
on 10 Feb 2018
Edited: Stephen23
on 10 Feb 2018
function outVec = fn_updateArray(newValue)
persistent newVec;
newVec = [newVec(max(1,end-5):end),newValue];
outVec = newVec;
end
and tested:
>> fn_updateArray(1)
ans = 1
>> fn_updateArray(2)
ans =
1 2
>> fn_updateArray(3)
ans =
1 2 3
>> fn_updateArray(4)
ans =
1 2 3 4
>> fn_updateArray(5)
ans =
1 2 3 4 5
>> fn_updateArray(6)
ans =
1 2 3 4 5 6
>> fn_updateArray(7)
ans =
1 2 3 4 5 6 7
>> fn_updateArray(8)
ans =
2 3 4 5 6 7 8
>> fn_updateArray(9)
ans =
3 4 5 6 7 8 9
>>
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