Вы можете связать значения 'x', используя панд, а затем вместо этого использовать гистограмму.
import pandas as pd
import matplotlib.pyplot as plt
df = pd.DataFrame({'Duration':[116.15, 120.45,118.92,7.02,73.93, 117.53, 4.4, 111.03, 4.35]})
df['Code'] = [65,65,65,66,66,66,66,66,66]
df['Seq.'] = [1,1,1,1,2,1,2,1,1]
df
Duration Code Seq.
0 116.15 65 1
1 120.45 65 1
2 118.92 65 1
3 7.02 66 1
4 73.93 66 2
5 117.53 66 1
6 4.40 66 2
7 111.03 66 1
8 4.35 66 1
df['bin'] = pd.cut(df['Duration'],10, labels=False)
df
Duration Code Seq. bin
0 116.15 65 1 9
1 120.45 65 1 9
2 118.92 65 1 9
3 7.02 66 1 0
4 73.93 66 2 5
5 117.53 66 1 9
6 4.40 66 2 0
7 111.03 66 1 9
8 4.35 66 1 0
x1 = df.loc[df.Code==65, 'bin']
x2 = df.loc[df.Code==66, 'bin']
y1 = df.loc[df.Code==65, 'Seq.']
y2 = df.loc[df.Code==66, 'Seq.']
plt.bar(x1, y1)
plt.bar(x2, y2)
plt.show()