If loop issue help

9 次查看（过去 30 天）
Ricardo jose
Ricardo jose 2021-3-23
回答： Star Strider 2021-3-23
Hello everyone, Im trying to evaluate "Acceleration_Value" and categoryze them as 1, 2 or 3 to depending on thei're value. Im having the issue that ds_mapping an array, stays completly full of 0, what am i doing wrong?
Acceleration_Value= abs(Acceleration); % Obtaining absolute values for acceleration/deceleration
ds_mapping=zeros(size(Acceleration)); % Creating variable to store evaluated values
i= ds ;
if 0.7 <= i & i>= 2.79 %#ok<AND2>
ds_mapping= 1;
elseif 2.79 < i & i >= 3.63 %#ok<AND2>
ds_mapping= 2;
elseif 3.63 < i & i >= 6.5 %#ok<AND2>
ds_mapping= 3;
end
  2 个评论
Jan
Jan 2021-3-23
There are no "if loops" in any programming language I know.
Ricardo jose
Ricardo jose 2021-3-23
the "if" condition then. By looking code can you understand what im struggling with?

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回答（2 个）

Star Strider
Star Strider 2021-3-23
An easier way to code that is to use an anonymous function:
ds_mapping = @(i) ((0.7 <= i) & (i>= 2.79 )).*1 + ((2.79 < i) & (i >= 3.63 )).*2 + ((3.63 < i) & (i >= 6.5 )).*3;
ds = linspace(0, 7);
figure
plot(ds, ds_mapping(ds))
grid
See the documentation on Anonymous Functions for details.
Jan
Jan 2021-3-23
编辑：Jan 2021-3-23
The if command is not a loop. It requires a scalar condition. You provide vectors, so Matlab inserts an all() automatically.
The "%#ok<AND2>" seems to show, that you have ignored another hint of the editor already: The case 0.7 <= i & i>= 2.79 canbe simplified to i >= 2.79. The same happens for the other branches. It is a good idea not to disable the warnings, but to fix the reason of the warnings.
Do you mean:
if 0.7 <= i & i <= 2.79
% ^ not > ?! Same in the other cases
end
Solution: Either create a loop or use logical indexing. With the data you have posted, both will not run:
ds_mapping=zeros(size(Acceleration)); % Creating variable to store evaluated values
i= ds ;
What is ds ?
  2 个评论
Ricardo jose
Ricardo jose 2021-3-23
ds is a "diff(time)"
Jan
Jan 2021-3-23
You did not mention a variable called "time" yet...

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