4.2. DataFrame Attributes¶
df.columnsdf.indexdf.values
4.2.1. SetUp¶
>>> import pandas as pd
>>> import numpy as np
>>> np.random.seed(0)
>>>
>>>
>>> df = pd.DataFrame(
... columns = ['Morning', 'Noon', 'Evening', 'Midnight'],
... index = pd.date_range('1999-12-30', periods=7),
... data = np.random.randn(7, 4))
>>>
>>> df
Morning Noon Evening Midnight
1999-12-30 1.764052 0.400157 0.978738 2.240893
1999-12-31 1.867558 -0.977278 0.950088 -0.151357
2000-01-01 -0.103219 0.410599 0.144044 1.454274
2000-01-02 0.761038 0.121675 0.443863 0.333674
2000-01-03 1.494079 -0.205158 0.313068 -0.854096
2000-01-04 -2.552990 0.653619 0.864436 -0.742165
2000-01-05 2.269755 -1.454366 0.045759 -0.187184
4.2.2. Columns¶
Get column names:
>>> df.columns
Index(['Morning', 'Noon', 'Evening', 'Midnight'], dtype='object')
Set column names:
>>> df.columns = ['A', 'B', 'C', 'D']
>>> df
A B C D
1999-12-30 1.764052 0.400157 0.978738 2.240893
1999-12-31 1.867558 -0.977278 0.950088 -0.151357
2000-01-01 -0.103219 0.410599 0.144044 1.454274
2000-01-02 0.761038 0.121675 0.443863 0.333674
2000-01-03 1.494079 -0.205158 0.313068 -0.854096
2000-01-04 -2.552990 0.653619 0.864436 -0.742165
2000-01-05 2.269755 -1.454366 0.045759 -0.187184
>>>
>>> df.columns
Index(['A', 'B', 'C', 'D'], dtype='object')
4.2.3. Indexes¶
Get index:
>>> df.index
DatetimeIndex(['1999-12-30', '1999-12-31', '2000-01-01', '2000-01-02',
'2000-01-03', '2000-01-04', '2000-01-05'],
dtype='datetime64[ns]', freq='D')
Set index:
>>> df.index = [0, 1, 2, 3, 4, 5, 6]
>>> df
A B C D
0 1.764052 0.400157 0.978738 2.240893
1 1.867558 -0.977278 0.950088 -0.151357
2 -0.103219 0.410599 0.144044 1.454274
3 0.761038 0.121675 0.443863 0.333674
4 1.494079 -0.205158 0.313068 -0.854096
5 -2.552990 0.653619 0.864436 -0.742165
6 2.269755 -1.454366 0.045759 -0.187184
>>>
>>> df.index
Int64Index([0, 1, 2, 3, 4, 5, 6], dtype='int64')
4.2.4. Values¶
Get values:
>>> df.values
array([[ 1.76405235, 0.40015721, 0.97873798, 2.2408932 ],
[ 1.86755799, -0.97727788, 0.95008842, -0.15135721],
[-0.10321885, 0.4105985 , 0.14404357, 1.45427351],
[ 0.76103773, 0.12167502, 0.44386323, 0.33367433],
[ 1.49407907, -0.20515826, 0.3130677 , -0.85409574],
[-2.55298982, 0.6536186 , 0.8644362 , -0.74216502],
[ 2.26975462, -1.45436567, 0.04575852, -0.18718385]])
You cannot modify values:
>>> values = np.zeros_like(df.values)
>>> values
array([[0., 0., 0., 0.],
[0., 0., 0., 0.],
[0., 0., 0., 0.],
[0., 0., 0., 0.],
[0., 0., 0., 0.],
[0., 0., 0., 0.],
[0., 0., 0., 0.]])
>>>
>>> df.values = values
Traceback (most recent call last):
AttributeError: property 'values' of 'DataFrame' object has no setter