[英]filter time-series pandas dataframe by column value
这个问题是这个问题的附加问题: filter multi-indexed grouped pandas dataframe
我希望从大于零的第一个value
开始的date
之后的所有数据(按时间)。 (适用于每个id
)
示例输入数据:
id timestamp date value
1 2001-01-01 2001-05-01 1
1 2001-10-01 2001-05-01 0
1 2001-10-02 2001-05-01 1
1 2001-10-03 2001-05-01 0
1 2001-10-04 2001-05-01 1
想要的 Output 数据示例:
id timestamp date value
1 2001-10-02 2001-05-01 1
1 2001-10-03 2001-05-01 0
1 2001-10-04 2001-05-01 1
首先按Series.gt
过滤另一列,然后创建GroupBy.cumsum
,过滤大于0
并最后添加删除的值DataFrame.reindex
:
df['timestamp'] = pd.to_datetime(df['timestamp'])
df['date'] = pd.to_datetime(df['date'])
df = df.sort_values(['id','timestamp'])
m = df['timestamp'].gt(df['date'])
m1 = df[m].groupby('id')['value'].cumsum().gt(0).reindex(df.index, fill_value=False)
df = df[m1]
print (df)
id timestamp date value
2 1 2001-10-02 2001-05-01 1
3 1 2001-10-03 2001-05-01 0
4 1 2001-10-04 2001-05-01 1
用Series.where
替换列的另一个想法:
df['timestamp'] = pd.to_datetime(df['timestamp'])
df['date'] = pd.to_datetime(df['date'])
df = df.sort_values(['id','timestamp'])
m = df['timestamp'].gt(df['date'])
m1 = df.assign(value = df['value'].where(m, 0)).groupby('id')['value'].cumsum().gt(0)
df = df[m1]
print (df)
id timestamp date value
2 1 2001-10-02 2001-05-01 1
3 1 2001-10-03 2001-05-01 0
4 1 2001-10-04 2001-05-01 1
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