The previous chapters focused on different types of data warping processes and NumPy、pandas And other library features . Over time ,pandas Developed more functions for advanced users . This chapter is about in-depth study pandas Advanced features of .
This section introduces pandas The classification type of . I will show you by using it , Improve performance and memory utilization . I will also introduce some tools for using classified data in statistics and machine learning .
A column in a table usually has repeated small sets with different values . We have learned unique and value_counts, They can extract different values from the array , And calculate the frequency separately ：
In [10]: import numpy as np; import pandas as pd
In [11]: values = pd
