Pearson product-moment correlation coefficient. About algorithm https://en.wikipedia.org/wiki/Pearson_product-moment_correlation_coefficient
pip install correlation-pearson
from correlation_pearson.code import CorrelationPearson
dmitry = [1, 2, 3, 5, 7, 8]
joseph = [1, 3, 4, 5, 7, 9]
correlation = CorrelationPearson()
print correlation.result(dmitry, joseph)
0.981460802132