Question

我有一个pandas DataFrame，并将index设置为DateTime列：

WFM = naToZero(WFM)

我需要插入数据。但是，这个索引后来阻止我做

data['DateTime'] = pandas.to_datetime (data['DateTime'])
data = data.set_index('DateTime')

其中data = data[pandas.to_datetime (data['DateTime']) <= cutoff]是某个日期时间。我怎么能这样做呢？

Answer 1

对于比较.index，您似乎需要DatetimeIndex：

data['DateTime'] = pandas.to_datetime (data['DateTime'])
data = data.set_index('DateTime')
data = data[data.index <= cutoff]

同样排序DatetimeIndex使用loc：

data1 = data1.loc[:cutoff]

样品：

rng = pd.date_range('2017-04-03', periods=10)
data = pd.DataFrame({'a': range(10)}, index=rng)  
print (data)
            a
2017-04-03  0
2017-04-04  1
2017-04-05  2
2017-04-06  3
2017-04-07  4
2017-04-08  5
2017-04-09  6
2017-04-10  7
2017-04-11  8
2017-04-12  9

cutoff = '2017-04-08'
data1 = data[data.index <= cutoff]
print (data1)
            a
2017-04-03  0
2017-04-04  1
2017-04-05  2
2017-04-06  3
2017-04-07  4
2017-04-08  5

data1 = data1.loc[:cutoff]
print (data1)
            a
2017-04-03  0
2017-04-04  1
2017-04-05  2
2017-04-06  3
2017-04-07  4
2017-04-08  5

感谢piRSquared：

data1 = data1[:cutoff]
print (data1)
            a
2017-04-03  0
2017-04-04  1
2017-04-05  2
2017-04-06  3
2017-04-07  4
2017-04-08  5

Pandas以索引列为条件

1 个答案: