In-depth understanding of Pandas in python (code examples)

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1. Filter

First create a 6X4 matrix data.

dates = pd.date_range('20180830', periods=6)
df = pd.DataFrame(np.arange(24).reshape((6,4)),index=dates, columns=['A','B','C','D'])
print(df)

Print:

             A   B   C   D
2018-08-30   0   1   2   3
2018-08-31   4   5   6   7
2018-09-01   8   9  10  11
2018-09-02  12  13  14  15
2018-09-03  16  17  18  19
2018-09-04  20  21  22  23

Simple filtering

If we want to select the data in DataFrame, two ways are described below, they can To achieve the same goal:

print(df['A'])
print(df.A)

"""
2018-08-30     0
2018-08-31     4
2018-09-01     8
2018-09-02    12
2018-09-03    16
2018-09-04    20
Freq: D, Name: A, dtype: int64
"""

To make the selection span multiple rows or columns:

print(df[0:3])
 
"""
            A  B   C   D
2018-08-30  0  1   2   3
2018-08-31  4  5   6   7
2018-09-01  8  9  10  11
"""

print(df['20180830':'20180901'])

"""
            A  B   C   D
2018-08-30  0  1   2   3
2018-08-31  4  5   6   7
2018-09-01  8  9  10  11
"""

If df[3:3] will be an empty object. The latter selects data between the tags 20180830 to 20180901, and includes these two tags .

You can also select via loc, iloc, ix.

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