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How to add certain elements of an array

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Alan Keenan
Alan Keenan 2020-8-25
评论： Alan Keenan 2020-8-25
I have two 200 x 200 arrays of pixel values.
They are all negative values representing -dB values
All of the signal pixel values are >= -20.
All other pixel values (no signal) have been forced to -60.
I want to add both arrays so that only the signal pixels are added to have a summated signal intensity.
This relates to TFM imaging in Ultrasonics.
  2 个评论
MaHa
MaHa 2020-8-25
Convert your -60 values into NaNs :
noSignal = find(A == -60);
A(noSignal = NaN);
Then do your addition
Alan Keenan
Alan Keenan 2020-8-25
Thanks for your answer, however, there appears to be a problem with the syntax of A(noSignal = NaN);
I entered
noSignal = find(img_dbLL == -60);
img_dbLL(noSignal = NaN);
When trying to run, I get the following message:
Incorrect use of '=' operator. To assign a value to a variable, use '='. To compare values for equality, use
'=='.

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采纳的回答

Matt J
Matt J 2020-8-25
编辑：Matt J 2020-8-25
I'll call your two arrays A and B.
map=A<-20 | B<-20;
result=A+B;
result(map)=-60;
  3 个评论
显示 1更早的评论
Matt J
Matt J 2020-8-25
You're welcome, but please Accept-click the asnwer if your issue is resolved.

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