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 =

    0.4100
    0.2500
    0.3340
         0
    0.5500
    0.6250
    0.7500
    0.3330
         0

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?

Answer 1

[Matt Kindig]

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);

[T]

I think so. What if they aren't?

[Image Analyst]

If they aren't the same size, you'd better figure out why not, or how to interpret that situation, because it won't make sense and the code won't run.

[T]

Okay. What was provided above works. However, would you know why I would get a continuous plot as opposed to a discrete?

Should I just use stem as opposed to plot?

[Matt Kindig]

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]

Actually stairs(Time,Value) gave me what I wanted.

Can you respond to my other thread?

http://www.mathworks.com/matlabcentral/answers/51019-synchronize-time-from-a-database-and-csv-file-and-plot