Editing contents of a labview array

[mlgpzz]

Hi all,

sorry I am new here. I have an array I of indices and an array A of zeros, both integer valued. I am looking for a way to increment by one the elements of A that corresponds to the indices in I. In python for example it would be:

for i in range(0, len(A)-1):
    A[I[i]] += 1

or in C:

 for( i = 0; i < sizeof(I)/sizeof(I[0]); i++ ) {
    A[ I[i] ]++;
}

or in Matlab:

for ii = 1:numel(I)
    A(I(ii)) = A(I(ii))+1; 
end

So far I made use of a for loop and then I use a) a "In place element" structure with a Index/replace function or b) a "Replace array subset" function, and a postincrement function:

The problem is, in both cases the output just keep in memory the last change, i.e. if

A = [0 1 2]
I = [0 0 1]

I would expect as an output:

[2 2 2]

while what I get is:

[0 2 2]

I hope I state the problem in a clear way. Sorry again I am new to this community. I tried to search for a solution but I guess I am missing something more fundamental here. Any help would be greatly apprciated

Best,

M

[dan_u · Accepted solution]

The fundamental thing you're missing are shift registers. Use these to store values between loop iterations. Otherwise you keep modifying the original array in each iteration.

[mlgpzz]

thanks a lot dan_u

indeed, replacing with shift register does the job

Any idea which one of the two solutions I listed in the first post is the most efficient?

Best,

M

[crossrulz]

As previously stated, you just need a shift register.

Also, you do not need to wire up the N on the FOR loop.  The reason is because the loop known how many iterations to perform based on the Autoindexing array.

[crossrulz]

---

@mlgpzz wrote:

Any idea which one of the two solutions I listed in the first post is the most efficient?

---

With the latest compiler, I am fairly certain it turns out to be the same machine code.  So then it just becomes a matter of readability.  Personally, I find the In Place Element Structure to be easier to look at.

[stevem181]

Dan is correct.

Also you don't need to connect the "N" input. 

The "indicies" array is set to auto-index.