熊猫开发新手。如何使用之前看到的列中包含的值转发填充DataFrame?
自包含的例子:
print(ohlc)
Open High Low Close
2017-07-23 03:13:00 1.0 5.0 1.0 5.0
2017-07-23 03:14:00 NaN NaN NaN NaN
2017-07-23 03:15:00 5.0 5.0 2.0 2.0
2017-07-23 03:16:00 NaN NaN NaN NaN
这会产生以下DataFrame:
Open High Low Close
2017-07-23 03:13:00 1.0 5.0 1.0 5.0
2017-07-23 03:14:00 5.0 5.0 5.0 5.0
2017-07-23 03:15:00 5.0 5.0 2.0 2.0
2017-07-23 03:16:00 2.0 2.0 2.0 2.0
我想从最后一个DataFrame转到这样的事情:
column2fill = 'Close'
ohlc[column2fill] = ohlc[column2fill].ffill()
print(ohlc)
Open High Low Close
2017-07-23 03:13:00 1.0 5.0 1.0 5.0
2017-07-23 03:14:00 NaN NaN NaN 5.0
2017-07-23 03:15:00 5.0 5.0 2.0 2.0
2017-07-23 03:16:00 NaN NaN NaN 2.0
因此,“关闭”前向中先前看到的值会填充整行,直到看到新的填充行。这样填充“关闭”列非常简单:
{{1}}
但有没有办法在03:14:00和03:16:00行填充这些行的'Close'值?有没有办法在一步中使用一个前向填充而不是先填充“关闭”列?
答案 0 :(得分:2)
您似乎需要assign
ffill
然后bfill
每行axis=1
,但必需的NaN
行:
df = ohlc.assign(Close=ohlc['Close'].ffill()).bfill(axis=1)
print (df)
Open High Low Close
2017-07-23 03:13:00 1.0 5.0 1.0 5.0
2017-07-23 03:14:00 5.0 5.0 5.0 5.0
2017-07-23 03:15:00 5.0 5.0 2.0 2.0
2017-07-23 03:16:00 2.0 2.0 2.0 2.0
与...相同:
ohlc['Close'] = ohlc['Close'].ffill()
df = ohlc.bfill(axis=1)
print (df)
Open High Low Close
2017-07-23 03:13:00 1.0 5.0 1.0 5.0
2017-07-23 03:14:00 5.0 5.0 5.0 5.0
2017-07-23 03:15:00 5.0 5.0 2.0 2.0
2017-07-23 03:16:00 2.0 2.0 2.0 2.0