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

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Thomas Hyatt
Thomas Hyatt 2023 年 3 月 18 日
コメント済み: John D'Errico 2023 年 3 月 19 日
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?

回答 (1 件)

John D'Errico
John D'Errico 2023 年 3 月 18 日
編集済み: John D'Errico 2023 年 3 月 18 日
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.
  2 件のコメント
Walter Roberson
Walter Roberson 2023 年 3 月 19 日
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
John D'Errico
John D'Errico 2023 年 3 月 19 日
Good point about the 'stable' option, necessary if you want to leave the order unchanged in a decreasing sequence.

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