1. A method comprising: accessing seed metadata, the seed metadata describing a seed, the seed being a basis on which a station library is to be defined; generating a station descriptor profile based on the seed metadata, the station descriptor profile defining a genre composition of the station library; generating a candidate set based on the seed metadata, the candidate set comprising a plurality of candidate media files; for each candidate media file in the candidate set: computing a similarity score associated with the candidate media file, the similarity score including a measure of similarity between the candidate media file and the station descriptor profile; computing one or more boost values associated with the candidate media file based on candidate metadata describing the candidate media file; determining a relevancy score associated with the candidate media file based on the similarity score and the one or more boost values associated with the candidate media file, the relevancy score providing a basis for selecting the candidate media file for inclusion in the station library; and machine-generating a station set including a portion of the candidate set selected based on the relevancy scores associated with the plurality of candidate media files included in the candidate set, the machine-generated station set defining the station library by referencing each candidate media file in the selected portion of the candidate set.