Stellar mass fraction maps of NGC 3115, in four bins of metallicity, marginalised over age. For each panel, the metallicity bin limits are indicated on its top left corner, the mean stellar mass fraction on its top right corner, and the colour scheme by the colour bar at the top of the figure. Spaxels containing a stellar mass fraction lower than 0.03 are masked, considered below our uncertainties. The galaxy orientation is the same as Fig. 3. It is remarkable that the central 10′′ where the inner disc resides, are made of only metal-rich stars (panel d)). The disc component has very little metal-poor stars (panels a) and b)), and the spheroid of NGC 3115 has a flat distribution over the four metallicity bins, from metal-rich to metal-poor.