xdc_git_python_20210511/tutorials-master/numpy&pandas/12_selection.py

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"""
Please note, this code is only for python 3+. If you are using python 2+, please modify the code accordingly.
"""
from __future__ import print_function
import pandas as pd
import numpy as np

dates = pd.date_range('20130101', periods=6)
df = pd.DataFrame(np.random.randn(6,4), index=dates, columns=['A', 'B', 'C', 'D'])

print(df['A'], df.A)
print(df[0:3], df['20130102':'20130104'])

# select by label: loc
print(df.loc['20130102'])
print(df.loc[:,['A','B']])
print(df.loc['20130102', ['A','B']])

# select by position: iloc
print(df.iloc[3])
print(df.iloc[3, 1])
print(df.iloc[3:5,0:2])
print(df.iloc[[1,2,4],[0,2]])

# mixed selection: ix
print(df.ix[:3, ['A', 'C']])
# Boolean indexing
print(df[df.A > 0])