Split vector by value ranges?

2021 1 26
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更新时间：2021 1 28
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Given:
w=[2,8,3,30,4,50,100,200,4,80,500]
How can I turn the following into a single line of code?
r=w(w>0 & w<10)
s=w(w>10 & w<100)
t=w(w>100 & w<1000)
I tried variations of:
[r,s,t]=w(w>0 & w<10),w(w>10 & w<100),w(w>100 & w<1000)

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Stephen23
Stephen23 2021-1-26
编辑：Stephen23 2021-1-26
@Don Kelly: I removed all of those ```and ´´´ characters, and formatted your code correctly by simply selecting the text and clicking the CODE button.

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 采纳的回答

weikang zhao
weikang zhao 2021-1-26

1 个投票

Use anonymous functions, it allows you to implement quite complex functions in one line. MATLAB supports dot indexing into function call results, as in foo(arg).prop. Other forms of indexing into function call results (with parentheses such as foo(arg)(2) or with curly braces such as foo(arg){2}) are not supported. So, I used feval and anonymous functions to complete this function in disguise.
w=[2,8,3,30,4,50,100,200,4,80,500];
[r,s,t]=feval(@(x) x{:},arrayfun(@(a,b) w(w>a&w<b),[0,10,100],[10,100,1000],'UniformOutput',false));
have fun!

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Don Kelly
Don Kelly 2021-1-26
Thank you. There is much to unpack from this function that I am not familiar with.
feval is a function that just evaluates all functions passed to it.
idk what x is in this instance or why you use case array parens then selecting every element in the row
then you us @ but I don't see the handle that is created by using @, unless the handle is (x) and (a,b)
arrayfun is a function that applies the functionality passed to every element of the array so i guess you applied @(a,b) to every element in w where w is greater than a and less than b, but then how does arrayfun know the ranges to perform the function @(a,b) on?
It looks like your arrays [0,10,100] and [10,100,1000] must be what the @(a,b) function looks to for range but i dont get it.
why di you need to specify that the output should not return uniformly?
Don Kelly
Don Kelly 2021-1-26
I guess also is there a less advanced way?
weikang zhao
weikang zhao 2021-1-26
An anonymous function does not need to name the function handle, you can destroy it in place after using it like I did. You can view the output of arrayfun&`feval`, this will help you understand. `arrayfun` can apply function to each element of array, so
arrayfun(@(a,b) w(w>a&w<b),[0,10,100],[10,100,1000],'UniformOutput',false)
will get a cell array and three matrices are stored separately.

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Walter Roberson
Walter Roberson 2021-1-26

2 个投票

[r,s,t] = deal(w(w>0 & w<10),w(w>10 & w<100),w(w>100 & w<1000))

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Don Kelly
Don Kelly 2021-1-28
Thank you Walter,
I accepted weikang zhao's answer since it was functional and first. I wanted to say that I am really grateful for your answer as well.

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