Finding TP, TN, FP, FN using histc. First Input must be a real non-sparse numeric array (error)
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I am finding TP, TN, FP, FN (confusion matrix) of predicted and actual image. smapImg is the predicted/output image and gtImg is the actual/ground truth image.
TP = histc(smapImg(gtImg), 0:255);
FP = histc(smapImg(~gtImg), 0:255);
FN = histc(~smapImg(gtImg), 0:255);
TN = histc(~smapImg(~gtImg), 0:255);
I am getting this error "First Input must be a real non-sparse numeric array" while computing FN and TN, while TP and FP are computing correctely. Please help.
2 个评论
Steven Lord
2019-8-20
What does the following command display? Show all the columns as any of them may contain information important to understanding why you receive that error.
whos smapImg gtImg
Nataliya
2019-8-20
采纳的回答
The negation (~) is turnning the array into a logical array. As the error message indicates, the first input is expected to be numeric (not logical).
~smapImg(gtImg)
Example
t = uint8(rand(1,10))
class(t)
ans =
'uint8'
t2 = ~t;
class(t2)
ans =
'logical'
A reproduction of the error using the logical vector
histc(t2,1:3)
Error using histc
First Input must be a real non-sparse numeric array.
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