  We discuss the charge polarization in a generalized Rice-Mele model at
arbitrary particle filling per site as a model of charge ordered systems in one
dimension. The model possesses neither the conventional bond-centered inversion
symmetry nor the one site translation symmetry alone, but has combinations of
these symmetries. We show that the charge polarization in the ground state is
quantized by the combined symmetry and is characterized solely by the filling.
Especially, the polarization can be $1/2$ (mod 1) in the zero filling limit.
Under the open boundary condition, there exist excess charges accumulated near
edges of the system irrespective of existence or absence of edge modes.
Correspondingly, we decompose the polarization into a bulk contribution and an
edge contribution, and numerically demonstrate that the polarization is
dominated by the former (latter) when the energy gap is large (small). We also
discuss a simple generalization of our model and examine absence/existence of a
gapless edge mode protected by the inversion symmetry by introducing intra unit
cell and inter unit cell contributions of the charge polarization.
