Computer-readable media stores instructions that perform operations including receiving a first electronic document; determining a first information gain value associated with a first line that divides the first electronic document into a first portion and a second portion; determining a second information gain value associated with a second line that divides the first electronic document into a third portion and a fourth portion; and determining which of the first information gain value and second information gain value is greater. Information gain values are determined by calculating a difference between an entropy value associated with a line and an entropy value associated with an electronic document. Entropy values associated lines or electronic documents are determined based at least in part on document objects in the portions created by a line or an electronic document.