pandas 注意点
In [18]: a = a.head(10)
In [19]: a
Out[19]:
Unnamed: 0 temp second temp_interval
0 2019-03-25 02:54:21 55 2019-03-25 02:54:21 0
1 2019-03-25 02:54:22 55 2019-03-25 02:54:21 0
2 2019-03-25 02:54:23 55 2019-03-25 02:54:21 0
3 2019-03-25 02:54:24 55 2019-03-25 02:54:21 0
4 2019-03-25 02:54:25 55 2019-03-25 02:54:21 0
5 2019-03-25 02:54:26 55 2019-03-25 02:54:21 0
6 2019-03-25 02:54:27 55 2019-03-25 02:54:21 0
7 2019-03-25 02:54:28 55 2019-03-25 02:54:21 0
8 2019-03-25 02:54:29 55 2019-03-25 02:54:21 0
9 2019-03-25 02:54:30 55 2019-03-25 02:54:21 0
In [20]: a.temp_interval = [0, 1, 1, 1, 32, 3, 34, -1, -2, -3]
/home/yinhaibo/anaconda3/lib/python3.6/site-packages/pandas/core/generic.py:4405: SettingWithCopyWarning:
A value is trying to be set on a copy of a slice from a DataFrame.
Try using .loc[row_indexer,col_indexer] = value instead
See the caveats in the documentation: http://pandas.pydata.org/pandas-docs/stable/indexing.html#indexing-view-versus-copy
self[name] = value
In [21]: a[a.temp_interval < -2] = 0
/home/yinhaibo/anaconda3/bin/ipython:1: SettingWithCopyWarning:
A value is trying to be set on a copy of a slice from a DataFrame.
Try using .loc[row_indexer,col_indexer] = value instead
See the caveats in the documentation: http://pandas.pydata.org/pandas-docs/stable/indexing.html#indexing-view-versus-copy
#!/home/yinhaibo/anaconda3/bin/python
/home/yinhaibo/anaconda3/lib/python3.6/site-packages/pandas/core/indexing.py:543: SettingWithCopyWarning:
A value is trying to be set on a copy of a slice from a DataFrame.
Try using .loc[row_indexer,col_indexer] = value instead
See the caveats in the documentation: http://pandas.pydata.org/pandas-docs/stable/indexing.html#indexing-view-versus-copy
self.obj[item] = s
In [22]: a
Out[22]:
Unnamed: 0 temp second temp_interval
0 2019-03-25 02:54:21 55 2019-03-25 02:54:21 0
1 2019-03-25 02:54:22 55 2019-03-25 02:54:21 1
2 2019-03-25 02:54:23 55 2019-03-25 02:54:21 1
3 2019-03-25 02:54:24 55 2019-03-25 02:54:21 1
4 2019-03-25 02:54:25 55 2019-03-25 02:54:21 32
5 2019-03-25 02:54:26 55 2019-03-25 02:54:21 3
6 2019-03-25 02:54:27 55 2019-03-25 02:54:21 34
7 2019-03-25 02:54:28 55 2019-03-25 02:54:21 -1
8 2019-03-25 02:54:29 55 2019-03-25 02:54:21 -2
9 0 0 0 0
In [23]: a[a.temp_interval < -1].iloc[:, 3] = 0
/home/yinhaibo/anaconda3/lib/python3.6/site-packages/pandas/core/indexing.py:543: SettingWithCopyWarning:
A value is trying to be set on a copy of a slice from a DataFrame.
Try using .loc[row_indexer,col_indexer] = value instead
See the caveats in the documentation: http://pandas.pydata.org/pandas-docs/stable/indexing.html#indexing-view-versus-copy
self.obj[item] = s
In [24]: a
Out[24]:
Unnamed: 0 temp second temp_interval
0 2019-03-25 02:54:21 55 2019-03-25 02:54:21 0
1 2019-03-25 02:54:22 55 2019-03-25 02:54:21 1
2 2019-03-25 02:54:23 55 2019-03-25 02:54:21 1
3 2019-03-25 02:54:24 55 2019-03-25 02:54:21 1
4 2019-03-25 02:54:25 55 2019-03-25 02:54:21 32
5 2019-03-25 02:54:26 55 2019-03-25 02:54:21 3
6 2019-03-25 02:54:27 55 2019-03-25 02:54:21 34
7 2019-03-25 02:54:28 55 2019-03-25 02:54:21 -1
8 2019-03-25 02:54:29 55 2019-03-25 02:54:21 -2
9 0 0 0 0
In [25]: a[a.temp_interval < -1][] = 0
python3
python2
变特定列值的方法
In [28]: b.iloc[list(b[b.b>5].index), :]
Out[28]:
a time b
1 99 99 99
3 3 2018-01-04 00:00:00 6
In [29]: b.iloc[list(b[b.b>5].index), :].b
Out[29]:
1 99
3 6
Name: b, dtype: int64
In [30]: b.iloc[list(b[b.b>5].index), :].b = 99999
/home/yinhaibo/anaconda3/lib/python3.6/site-packages/pandas/core/generic.py:4405: SettingWithCopyWarning:
A value is trying to be set on a copy of a slice from a DataFrame.
Try using .loc[row_indexer,col_indexer] = value instead
See the caveats in the documentation: http://pandas.pydata.org/pandas-docs/stable/indexing.html#indexing-view-versus-copy
self[name] = value
In [31]: b
Out[31]:
a time b
0 3 2018-01-01 00:00:00 5
1 99 99 99
2 0 0 0
3 3 2018-01-04 00:00:00 6
4 0 0 0
In [32]: b.loc[list(b[b.b>5].index), 'b'] = 99999
In [33]: b
Out[33]:
a time b
0 3 2018-01-01 00:00:00 5
1 99 99 99999
2 0 0 0
3 3 2018-01-04 00:00:00 99999
4 0 0 0
In [34]: b[b.b < 6].b = 555
/home/yinhaibo/anaconda3/lib/python3.6/site-packages/pandas/core/generic.py:4405: SettingWithCopyWarning:
A value is trying to be set on a copy of a slice from a DataFrame.
Try using .loc[row_indexer,col_indexer] = value instead
See the caveats in the documentation: http://pandas.pydata.org/pandas-docs/stable/indexing.html#indexing-view-versus-copy
self[name] = value
In [35]: b[b.b < 6].loc[:, 'b'] = 55555555
/home/yinhaibo/anaconda3/lib/python3.6/site-packages/pandas/core/indexing.py:543: SettingWithCopyWarning:
A value is trying to be set on a copy of a slice from a DataFrame.
Try using .loc[row_indexer,col_indexer] = value instead
See the caveats in the documentation: http://pandas.pydata.org/pandas-docs/stable/indexing.html#indexing-view-versus-copy
self.obj[item] = s
In [36]: b
Out[36]:
a time b
0 3 2018-01-01 00:00:00 5
1 99 99 99999
2 0 0 0
3 3 2018-01-04 00:00:00 99999
4 0 0 0
In [37]: b.loc[:, 'b'][b.b < 6] = 55555555
/home/yinhaibo/anaconda3/bin/ipython:1: SettingWithCopyWarning:
A value is trying to be set on a copy of a slice from a DataFrame
See the caveats in the documentation: http://pandas.pydata.org/pandas-docs/stable/indexing.html#indexing-view-versus-copy
#!/home/yinhaibo/anaconda3/bin/python
In [38]: b
Out[38]:
a time b
0 3 2018-01-01 00:00:00 55555555
1 99 99 99999
2 0 0 55555555
3 3 2018-01-04 00:00:00 99999
4 0 0 55555555
In [39]: b.iloc[:, 2] = 666
In [40]: b
Out[40]:
a time b
0 3 2018-01-01 00:00:00 666
1 99 99 666
2 0 0 666
3 3 2018-01-04 00:00:00 666
4 0 0 666
# data.drop(['temp', 'second'], axis=1, inplace=True)
#
# data[data.temp_interval < -3] = 0
# data[data.temp_interval > 0] = 0
###################################################
# data.loc[:, 'temp_interval'][data.temp_interval < -3] = 0
# data.loc[:, 'temp_interval'][data.temp_interval > 0] = 0
# data.drop(['temp', 'second'], axis=1, inplace=True)
data.loc[list([data.temp_interval < -3].index), 'temp_interval'] = 0
data.loc[list([data.temp_interval > 0].index), 'temp_interval'] = 0
data.drop(['temp', 'second'], axis=1, inplace=True)