Comparison between the characteristic metallicities (at 0.4 × R₂₅; left) and metallicity gradients (right) obtained by De Vis et al. (2019) for DustPedia galaxies with the Kobulnicky & Kewley (2004) calibration (on ordinates), and the same values from Pilyugin et al. (2014) and Zurita et al. (2021, on abscissae; red and blue datapoints, respectively). For each galaxy, characteristic metallicities and gradients on abscissae have been derived from the original data using the same value for R₂₅ (from De Vis et al. 2019). Grey and black datapoints on the left panel show the comparison with Pilyugin et al. (2014) and Zurita et al. (2021), respectively, once the characteristic metallicity of De Vis et al. (2019) has been corrected by 0.45 dex. De Vis et al. (2019) have 58 galaxies in common with Pilyugin et al. (2014) (9 with Zurita et al. 2021). Datapoints for the galaxies used in this work are shown with a circle.