[英]How to update a column in pandas DataFrame based on column from another DataFrame
[英]How to add a column to pandas dataframe based on time from another column
我正在尝试根据我选择的时隙在pandas dataframe
添加一列,以插入Morning
, Evening
或Afternoon
。
我正在尝试的代码如下:
df_agg['timeOfDay'] = df_agg.apply(lambda _: '', axis=1)
for i in range (len(df_agg)):
if df_agg['time_stamp'].iloc[i][0].hour < 12:
df_agg['timeOfDay'].iloc[i] = 'Morning'
elif df_agg['time_stamp'].iloc[i][0].hour < 17 & df_agg['time_stamp'].iloc[i][0].hour > 12:
df_agg['timeOfDay'].iloc[i] = 'Afternoon'
else:
df_agg['timeOfDay'].iloc[i] = 'Evening'
当我返回df_agg
,它返回一个空的timeOfDay
列。 尝试根据一天中的时间将这些元素插入行时,有人知道我在做什么吗?
pandas
使用pd.cut
将其按垃圾桶pd.cut
并提供标签。 此方法也使创建更细粒度的时隙变得很简单
df_agg.assign(
timeOfDay=pd.cut(
df_agg.time_stamp.dt.hour,
[-1, 12, 17, 24],
labels=['Morning', 'Afternoon', 'Evening']))
numpy
使用searchsorted
hours = df_agg.time_stamp.dt.hour.values
times = np.array(['Morning', 'Afternoon', 'Evening'])
df_agg.assign(timeOfDay=times[np.array([12, 17]).searchsorted(hours)])
既屈服
时间测试
小数据集
大数据集
start = pd.to_datetime('2015-02-24 10:00:00')
rng = pd.date_range(start, periods=10000, freq='1h')
df_agg = pd.DataFrame({'time_stamp': rng, 'a': range(len(rng))})
设定
借用@jezrael的设置df_agg
start = pd.to_datetime('2015-02-24 10:00:00')
rng = pd.date_range(start, periods=12, freq='1h')
df_agg = pd.DataFrame({'time_stamp': rng, 'a': range(len(rng))})
print (df_agg)
我认为您可以使用double numpy.where
,请检查是否有必要将<
更改为<=
或>
更改为>=
:
start = pd.to_datetime('2015-02-24 10:00:00')
rng = pd.date_range(start, periods=12, freq='1h')
df_agg = pd.DataFrame({'time_stamp': rng, 'a': range(12)})
print (df_agg)
a time_stamp
0 0 2015-02-24 10:00:00
1 1 2015-02-24 11:00:00
2 2 2015-02-24 12:00:00
3 3 2015-02-24 13:00:00
4 4 2015-02-24 14:00:00
5 5 2015-02-24 15:00:00
6 6 2015-02-24 16:00:00
7 7 2015-02-24 17:00:00
8 8 2015-02-24 18:00:00
9 9 2015-02-24 19:00:00
10 10 2015-02-24 20:00:00
11 11 2015-02-24 21:00:00
hours = df_agg.time_stamp.dt.hour.values
df_agg['timeOfDay'] = np.where(hours <= 12, 'Morning',
np.where(hours >= 17, 'Evening', 'Afternoon'))
a time_stamp timeOfDay
0 0 2015-02-24 10:00:00 Morning
1 1 2015-02-24 11:00:00 Morning
2 2 2015-02-24 12:00:00 Morning
3 3 2015-02-24 13:00:00 Afternoon
4 4 2015-02-24 14:00:00 Afternoon
5 5 2015-02-24 15:00:00 Afternoon
6 6 2015-02-24 16:00:00 Afternoon
7 7 2015-02-24 17:00:00 Evening
8 8 2015-02-24 18:00:00 Evening
9 9 2015-02-24 19:00:00 Evening
10 10 2015-02-24 20:00:00 Evening
11 11 2015-02-24 21:00:00 Evening
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