Remove or trim zeros 0 at the end only of a float[] samples array

Question

I am kind of new with C# and I was wondering if there is a function to remove specific values (0) at the end of an array of float?

For example:

float[] samples = {0.0, 4.0, 2.5, ..., 2.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0};

after the call I want my samples to be:

samples == {0.0, 4.0, 2.5, ..., 2.0}

Thank you for your help

Possibly related :[Remove element of a regular array](https://stackoverflow.com/q/457453/4977870) — Anas Alweish, Dec 06 '18 at 09:50

score 6 · Answer 1 · answered Dec 06 '18 at 09:46

6

I'd start by finding the final non-zero index:

int i = samples.Length - 1;
for( ; i >= 0; i--)
    if(samples[i] != 0.0F) break;

then I'd either copy that subset (0-i inclusive), or to avoid allocations I'd use a Span<T> to limit myself to that part without creating a new array:

var span = new Span<float>(samples, 0, i + 1);

answered Dec 06 '18 at 09:46

Marc Gravell

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`int i = samples.Length - 1; while(samples[i] == 0.0f) i--;` is another way to iterate over the array. – D.Go Dec 06 '18 at 09:55
@D.Go nice, I like that – Marc Gravell Dec 06 '18 at 10:00
additional notes: if you need to *store* the range, use `Memory` instead of `Span`, and access the `.Span` when you need it; or if you're in old-school .NET: `ArraySegment` would work too, but everything becomes manual – Marc Gravell Dec 06 '18 at 10:02
Clever use of span, but isn't it c# 7.2 feature? – Mihir Dave Dec 06 '18 at 10:03
@MihirDave indeed; if you look at the comment immediately above yours, I did suggest an alternative for the version-impaired – Marc Gravell Dec 06 '18 at 10:07

Leonid Dudnik · Answer 2 · 2018-12-09T11:21:46.073

float[] samples = { 0.0f, 4.0f, 2.5f, 2.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f };

var clean = new List<float>();
for (int i = 0; i <samples.Length; i++)
{
    if (i == 0)
    {
        if (samples[i] == 0.0f) clean.Add(samples[i]);
        continue;
    }
    if (samples[i] != 0.0f) clean.Add(samples[i]);
}

//clean.ToArray() = float[]

This may be better solution

float[] samples = { 0.0f, 4.0f, 2.5f, 2.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f };

List<float> clean = samples.ToList();
for(int i=clean.Count-1; i>0; i--)
{
    if (clean[i] == 0.0f) clean.RemoveAt(i);
    else break;
}

//clean.ToArray()

score 0 · Answer 3 · answered Dec 06 '18 at 13:27

For now, I've tried this, it works for what I want but I'm not sure it is the simplest:

                float[] samples = new float[AudioFeedbackList[i].GetComponent<AudioSource>().clip.samples * AudioFeedbackList[i].GetComponent<AudioSource>().clip.channels];

            List<float> sampi = new List<float>();
            sampi.AddRange(samples);
            int j = sampi.Count;

            while (sampi[j - 1] == 0.0f)
            {
                j--;
            }

            List<float> newSampi = new List<float>();
            for (int k = 0; k < j; k++)
            {
                newSampi.Add(sampi[k]);
            }


            samples = newSampi.ToArray();

Thank you for the feedback!

Remove or trim zeros 0 at the end only of a float[] samples array

3 Answers3