Figure 2  Exact p-value against Karlin ones (in log scale). Color refers to a range of sequence lengths: smaller than 100 in black (≃ 20 000 sequences), between 100 and 200 in red (≃ 40 000 sequences), between 200 and 500 in orange (≃ 90 000 sequences), between 500 and 1000 in yellow (≃ 30 000 sequences), between 1000 and 2 000 in blue (≃ 6 000 sequences) and greater than 2 000 in green (≃ 1 000 sequences). The solid line represents y = x. Range have been chosen for readability and few dots with exact p-value smaller than 10-30 are hence missing.