import seaborn

%matplotlib inline
import seaborn as sns
import pandas as pd
data = pd.DataFrame([['ENSP 438', 0, '2014-02-02'],
                     ['ENSP 438', 1, '2014-02-04'],
                     ['ENSP 438', 2, '2014-02-09'],
                     ['ENSP 438', 0, '2014-02-11'],
                     ['ENSP 438', 7, '2014-02-16'],
                     ['ENSP 438', 4, '2014-02-18'],
                     ['ENSP 438', 3, '2014-02-23'],
                     ['ENSP 438', 1, '2014-02-25'],
                     ['ENSP 322', 11, '2014-02-03'],
                     ['ENSP 322', 11, '2014-02-05'],
                     ['ENSP 322', 8, '2014-02-10'],
                     ['ENSP 322', 12, '2014-02-12'],
                     ['ENSP 322', 17, '2014-02-17'],
                     ['ENSP 322', 13, '2014-02-19'],
                     ['ENSP 322', 17, '2014-02-24'],
                     ['ENSP 322', 21, '2014-02-26'],
                     ['ENSP 430', -5, '2014-02-05'],
                     ['ENSP 430', -6, '2014-02-12'],
                     ['ENSP 430', -8, '2014-02-19'],
                     ['ENSP 430', -7, '2014-02-26'],
                     ['ENSP 202', 3, '2014-02-02'],
                     ['ENSP 202', 2, '2014-02-04'],
                     ['ENSP 202', 6, '2014-02-09'],
                     ['ENSP 202', 4, '2014-02-11'],
                     ['ENSP 202', -4, '2014-02-16'],
                     ['ENSP 202', 3, '2014-02-18'],
                     ['ENSP 202', 11, '2014-02-23'],
                     ['ENSP 202', 5, '2014-02-25'],
                     ['ENSP 418', 7, '2014-02-02'],
                     ['ENSP 418', 6, '2014-02-04'],
                     ['ENSP 418', 7, '2014-02-09'],
                     ['ENSP 418', 10, '2014-02-11'],
                     ['ENSP 418', -2, '2014-02-16'],
                     ['ENSP 418', 10, '2014-02-18'],
                     ['ENSP 418', 5, '2014-02-23'],
                     ['ENSP 418', 6, '2014-02-25'],
                     ['ENSP 302', 4, '2014-02-03'],
                     ['ENSP 302', 10, '2014-02-05'],
                     ['ENSP 302', 11, '2014-02-10'],
                     ['ENSP 302', 7, '2014-02-12'],
                     ['ENSP 302', 15, '2014-02-17'],
                     ['ENSP 302', 9, '2014-02-19'],
                     ['ENSP 302', 10, '2014-02-24'],
                     ['ENSP 302', 0, '2014-02-26'],
                     ['ENSP 303', -1, '2014-02-03'],
                     ['ENSP 303', 2, '2014-02-05'],
                     ['ENSP 303', 1, '2014-02-10'],
                     ['ENSP 303', 3, '2014-02-12'],
                     ['ENSP 303', 4, '2014-02-17'],
                     ['ENSP 303', 3, '2014-02-19'],
                     ['ENSP 303', 13, '2014-02-24'],
                     ['ENSP 303', 6, '2014-02-26']],
                     
                    columns=['class', 'num_students', 'date'])
sns.violinplot(data['num_students'], groupby=data['class'], inner="points")

<matplotlib.axes.AxesSubplot at 0x7fc2795c3f50>