Table 1.

Example of merging three metabolomics datasets (S1, S2, S3) into a unified feature space. Each column represents a unique metabolite, and each row corresponds to a dataset

Dataset	Met A	Met B	Met C	Met D	Met E
S1	1.2	3.4	NA	5.6	NA
S2	NA	2.1	4.3	NA	6.7
S3	0.9	NA	3.3	NA	7.1

“NA” indicates that the metabolite was not originally measured in that dataset. The final feature space is defined as the union of all metabolites across datasets