Colon syntax for creating a sequence of numbers that skips a given number?

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Thomas Hyatt 2023-3-18

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评论： John D'Errico 2023-3-19

I may be going crazy, but I remember both reading about and using a part of colon notation for creating a sequence of numbers (say 1:10 giving 1 2 3 4 5 6 7 8 9 10) but skipping a given number.

For instance, if I wanted 1:10 but to skip the number 5, it would yield 1 2 3 4 6 7 8 9 10.

I thought it was something like 1:~5:10, but that is certainly not the notation.

I know that

number = 5;
sequnce = [1:number-1 number+1:10];

would yield the same thing, but I distinctly remember a cleaner notation for it. I have been entirely unsuccessful in finding anything about it online. Does it actually exist, or is my memory making things up?

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Answer 1

John D'Errico 2023-3-18

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编辑：John D'Errico 2023-3-18

在 MATLAB Online 中打开

You can't, at least not directly. But it is quite simple. For example:

setdiff(1:10,3) % 1:10, missing 3
ans = 1×9
     1     2     4     5     6     7     8     9    10

There are probably other solutions too, as there always are, but I prefer this one. It is easy to understand, and easy to write.

The notation you remember is not anything in MATLAB, at least not currently. It may have been something in another language you recall.

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Walter Roberson 2023-3-19

在 MATLAB Online 中打开

Note that you may have to use the 'stable' option of setdiff.

setdiff(10:-1:1,3)
ans = 1×9
     1     2     4     5     6     7     8     9    10
setdiff(10:-1:1,3,'stable')
ans = 1×9
    10     9     8     7     6     5     4     2     1