get_unique_motif_score: Compute the enrichment score for a motif in the foreground...
In VoisinneG/MotifAll: Analysis of motifs in protein sequences

Compute the enrichment score for a motif in the foreground set as compared to the background set

1	get_unique_motif_score(df, idx_select, motif, match_central_letter = TRUE)

`df`	a data frame corresponding to set of background sequences as obtained by calling `sequence_to_df`. Could also be a vector of background sequences (with a fixed length) but will be slower.
`idx_select`	Indexes of foreground sequences in `x`. Note that the foreground set must be a subset of the background set.
`motif`	a motif
`match_central_letter`	keep only sequences that have the same central letter as the motif