How to replace all odd numbers with infinity using find()

I have a code that looks like this: C = randi([100,200],1000,1000);

How would I replace all the odd numbers with infinity using the find() function. I read up on find but I am unsure how to replace just the odd numbers.

Thank you in advance

[Adam Danz]

Please don't create duplicate questions

https://www.mathworks.com/matlabcentral/answers/484704-how-to-replace-all-odd-numbers-with-infinity-using-find

Answer 1

[Walter Roberson]

locations = find( Value_Is_Odd(C) );

where Value_Is_Odd is a function or expression that you write that takes in an array of values and returns a logical array of which entries are odd.

Hint: rem(), mod()

[timetry2]

But how would I replace the odd values with infinities?

[Walter Roberson]

locations would give you a vector list of index locations into C. You can assign something to all of those locations using the general forms

Array(Locations) = Value;   %for scalar Value to be assigned to all those places

or

Array(Locations) = ValueVector;  %for ValueVector being a vector the same size as Locations

[timetry2]

I'm sorry Im still confused. So, could you show me what my code would look like? Thank you in advance

[Adam Danz]

C is a matrix.

This line below will give you the row and column numbers that are TRUE in the find() inputs.

[rowNum, colNum] = find(. . .)

Or, as Walter explained, this version below gives you the linear index of locations.

locations = find(. . .)

Experiment with both versions to understand the outputs.

[Walter Roberson]

Look at this example:

A = 1:10
locations = [2 7 9]
A(locations) = -1

[Walter Roberson]

Further example:

A = 1:10;
locations = find(A > 5);
A(locations) = -1

[timetry2]

I understand the code now with the example. Thank you so much. However, is there a way to only retrieve odd numbers without having to manually input them after find?

[Walter Roberson]

Hint: rem(), mod()

[timetry2]

Thank you so much for your help

[timetry2]

I ended up with a code that looks like this:

C = randi([100,200],1000,1000);

evenIndices = rem(C,2) == 0

allTheEvenNumbers = C(evenIndices)

allTheEvenNumbers = allTheEvenNumbers -1

locations = find(allTheEvenNumbers);

C(locations) = Inf

However, the odd numbers are not being replaced by Inf. What am I doing wrong?

[Adam Danz]

Note, continued here

https://www.mathworks.com/matlabcentral/answers/484962-replace-odd-numbers-with-infinity