Conditional Entropy

ConditionalEntropy: Calculates conditional entropy (in bits) of Y, given X

H = ConditionalEntropy(Y,X)

H = calculated entropy of Y, given X (in bits)
Y = dependent variable (column vector)
X = independent variable(s)

Note 1: Each distinct value is considered a unique symbol.

Note 2: requires 'Entropy' and 'MutualInformation' functions

Example: 'X' (1 bit of entropy), 'Y' (2 bits of entropy)
Given 'X', 'Y's conditional entropy is 1 bit.

Note: Estimated entropy values are slightly less than true, due to finite sample size.

Y = ceil(4 * rand(1e3,1)); X = double(Y <= 2);
ConditionalEntropy(Y,X)