Function to fill an array given conditions.

Question

Andrew Czeizler 2019-3-13

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/449822-function-to-fill-an-array-given-conditions

评论： Adam 2019-3-13

Hi All,

I am trying to write a function to fill an array given conditions. basiclly the user inputs two variables a max and min and given these

values it creates two new row vectors, ph and date, which is a subset of an orignal vector.

My code is given below -

function [datenew,phnew] = subsetdata(date, ph, pressure, min, max)
%create empty array
datenew=cell(1,5000);
phnew=cell(1,5000);
%loop through each point
for i=1:size(pressure)
    %check condition
    if (pressure(i,:)>=min & pressure(i,:)<max)
        %fill array if condition met
        datenew{i}=date(i);
        phnew{i}=ph(i);
        
    end
end
end

2 个评论
显示无隐藏无

Andrew Czeizler 2019-3-13

编辑：Andrew Czeizler 2019-3-13

date, ph and pressure are row vectors. we go through and check pressure againes max and min. Then if at that point its between the two values we take date and ph at that index and fill and new vector. Returning a new vector date and ph which meets the conditions.

Adam 2019-3-13

What is your question?

Also, never use min and max as variable names. These are function names in Matlab and by creating variables with those names you hide the respective functions and make them inaccessible to use.

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Adam 2019-3-13

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/449822-function-to-fill-an-array-given-conditions#answer_365161

编辑：Adam 2019-3-13

在 MATLAB Online 中打开

validIdx = pressure >= minVal & pressure < maxVal;
datenew = date( validIdx );
phnew = ph( validIdx );

should do this for you without needing the loop and using logical indexing instead. I don't know why you are putting results in a cell array though. Never use a cell array when a numeric array will do the job.

2 个评论
显示无隐藏无

Andrew Czeizler 2019-3-13

编辑：Andrew Czeizler 2019-3-13

looking sharp!

Thank you :).

Will give it a try.

I was wondering, what should I use instead? nan()?

Best,

Andrew

Adam 2019-3-13

在 MATLAB Online 中打开

Ah, well, if you want to keep positions with NaNs inbetween then you will need to do it slightly different:

datenew = nan( size( date ) );
phnew = nan( size( date ) );
validIdx = pressure >= minVal & pressure < maxVal;
datenew( validIdx ) = date( validIdx );
phnew( validIdx ) = ph( validIdx );

请先登录，再进行评论。