  The definition of weighted entropy allows for easy calculation of the entropy
of the mixture of measures. In this paper we investigate the problem of
equivalent definition of the general entropy function in weighted form. We show
that under reasonable condition, which is satisfied by the well-known Shannon,
R\'enyi and Tsallis entropies, every entropy function can be defined
equivalently in the weighted way. As a corollary, we show how use the weighted
form to compute Tsallis entropy of the mixture of measures.
