Fig. 4

Examples of the mapping procedures (Greengenes into SILVA) on a set of nodes on the path from the Root to the species Persicus. a Strict mapping (top–down). From the root node we can match a path only down to the phylum level, hence all the nodes below the phylum level on the path in Greengenes are mapped to the phylum Bacteroidetes in SILVA. b Loose mapping (bottom–up). The node Persicus with species rank in Greengenes does not have a perfect match in SILVA, but its parent node Lewinella with genus rank has a match, therefore Persicus is mapped to the same node as Lewinella. In the path comparisons we consider only nodes that can be mapped perfectly themselves or whose descendants have perfect mappings. Here we consider the node Lewinella and all above, but leave out species node Persicus. c Visualization of the loose mapping from (b) as parallel sets and a heatmap with numeric values. Parallel sets plot show the “flow” of the mappings; the more parallel lines connecting the two bars, the better the overall mapping. Heatmap values are normalized by the row sums. A strong emphasis of the main diagonal indicates that the two taxonomies are compatible