How to add a number to an element of a vector which meets a certain criteria?

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Pree 2015-9-3

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https://ww2.mathworks.cn/matlabcentral/answers/239419-how-to-add-a-number-to-an-element-of-a-vector-which-meets-a-certain-criteria

评论： Star Strider 2015-9-3

采纳的回答： Star Strider

I have a vector which has sleep times. Its length is 915. But just for an example lets say,

t=[21.33; 22.45; 23.11; 23.67; 0.13; 1.56; 2.33];

The last 3 elements are times after midnight. So I want to add 24 to times after midnight. How can I do it? I tried using if statement.

if t<5

t=t+24

end

but this doesn't work.

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Star Strider 2015-9-3

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/239419-how-to-add-a-number-to-an-element-of-a-vector-which-meets-a-certain-criteria#answer_191215

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This works:

t=[21.33; 22.45; 23.11; 23.67; 0.13; 1.56; 2.33];
t(t<5) = t(t<5)+24
t =
33
45
11
67
13
56
33

This approach uses ‘logical indexing’ to specifically address only the elements you want. (Using decimal notation for the time makes this much easier!)

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Pree 2015-9-3

Thank you.

Star Strider 2015-9-3

My pleasure.

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