Best way to replace a portion of array

[clonzz]

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@ghighuphu wrote:
Could you post here one or two of your large arrays, please, dear clonzz?

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Initially I used 1000*1000 zeros elements with the last element being 1. Since you asked about the zeros thing, I used random number for each of the elements as attached in the picture. However, the result is the same.

[Yamaeda]

For the pure extract/replace the ordinary functions worked quite well, see attached.

/Y