Ignore elements in an array.

Question

T 2012-10-16

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/50955-ignore-elements-in-an-array

Hi. I am to plot Value vs. Time using the following data from a databasefile which I haven't included. But the output looks like the following:

Value =

Time =

1.0e+003 *
    3.4018
    3.4431
    3.4507
    3.4563
    3.4585
    3.4684
    3.4793
    3.4819
    3.5181
Value = []; % create a 0-by-0 matrix
Time = [];
    for i = 1:k      
        ValueID = ValueList(i,n);
            if ValueID > 0 % some Value id's are negative or zero - these are irrelevant
                index = find(ismember(cell2mat(Table1(:,1)),ValueID)==1); % locates the index
                Output   = Table{index,2};        
                ValueList(i,5) = Output; % Takes values from 5th column in databasefile
                ValueList(i,6) = 39.3700787*gwdWt; % convert from metres to inches and takes values from sixth row in databasefile
            %else
            end            
            Value = [Value;ValueList(i,6)] % structures value as a row.
            Time = [Time; ValueList(i,2)]
    end

So what I am asking is, how do I ignore the following

       0 and     3.4563,
also

0 and 3.5181?

Is that clear?

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Answer 1

Matt Kindig 2012-10-16

0
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https://ww2.mathworks.cn/matlabcentral/answers/50955-ignore-elements-in-an-array#answer_62092

在 MATLAB Online 中打开

Are Value and Time the same size? If so, you can just do this, using logical indexing (no loops):

deleteThese = (Value <= 0);
ValuesWithDeletions = Value(~deleteThese);
TimeWithDeletions = Time(~deleteThese);

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Matt Kindig 2012-10-16

在 MATLAB Online 中打开

What is a "discrete" plot vs. a "continuous" plot, in this context? Do you just mean a plot with connected points (i.e. lines), as opposed to just markers? If so, you can easily turn off the line to display only the "discrete" points. Do something like this:

plot(Time, Value, 'b.')

T 2012-10-16