H I mass content distribution. The left panel shows the logarithmic gas fraction, log(M_H I /M_⋆), versus the stellar mass log(M_⋆/M_⊙). The right column shows a violin plot of the H I mass relative distributions for all the sub-samples. The x-axis shows the relative distribution of all sub-samples. The lines show the median values (dashed) and the 25% and 75% percentiles (dotted). The S⁴G-LTG, S⁴G-ETG, ETG, and DG sub-samples are shown with blue triangles, down-pointing red triangles, orange stars, and purple circles, respectively. The numbers shown in the legend of the left panel indicate the number of galaxies with H I measurements in each sub-sample.