Secure information flow analysis aims to check that the execution of a program does not reveal information about secret data manipulated by this program. In this paper, we consider programs dealing with arrays; unlike most of existing works, we will not assume that arrays are homogeneous in terms of security levels. Some part of an array can be declared as secret whereas another part is public. Based on a pre-computed approximation of integer variables (serving as indices for arrays), we devise a type system such that typed programs do not leak unauthorized information. Soundness of our type system is proved by a non-interference theorem.