pandas 根据条件合并行

Question

大家好，我正在处理包含以下示例的数据集：

数据包含start_time、end_time、id和url。对于一个 id 和 url 组，我有不同的输入和输出值问题是输入值和输出值在不同的行中，我想填充缺失的 end_time/start_time 值。为此，我必须使用以下逻辑：

如果我在 start_time 中有值并且结束时间为空，那么考虑到 end_time >= [=59，我必须用最接近的 end_time 填充 end_time =] 并删除 used/matched 行
在所有 star_time 行被填充并删除 used/matched 行之后，仍然有一些空行 start_time，然后我必须填充 start_time 与 end_time.
如果没有为给定的 start_time 找到匹配的 end_time 值，那么我必须用相同的 start_time 值填充 end_time 值。

考虑到以上几点，预期结果应该与以下类似，我分两个阶段给出输出，以便于理解

用 start_time 填充匹配的 end_time 并删除 used/matched 行：
最终输出填充剩余的start_time/end_time值：

目前我正在使用以下方式来实现这一点，但我觉得它没有优化：

 def process(self, param, context):
    df = context['data']
    # df = df.drop_duplicates()
    key_cols = param['keys_cols']
    start_time_col = param['start_time_col']
    end_time_col = param['end_time_col']
    guid_col = param.get('guid_col','guid')
    df_groupby = df.groupby(key_cols).size().reset_index()
    final_dfs = []
    condition = ''
    for key in key_cols:
        if condition == '':
            condition = '(df[\''+str(key)+"\']==row[\'"+str(key)+"\'])"
        else:
            condition = condition + ' & ' +'(df[\'' + str(key) + "\']==row[\'" + str(key) + "\'])"
    for index, row in df_groupby.iterrows():
        sub_df = df[eval(condition)]
        if sub_df[start_time_col].isnull().sum() != len(sub_df[start_time_col]) and (sub_df[end_time_col].isnull().sum() != len(sub_df[end_time_col])):
            sub_df = sub_df.sort_values([start_time_col, end_time_col], ascending=True)
            subdf_start_time_not_null = sub_df[sub_df[start_time_col].notnull()]
            subdf_end_time_not_null = sub_df[sub_df[end_time_col].notnull()]
            subdf_end_time_not_null['combined'] = subdf_end_time_not_null[end_time_col] +"__"+ subdf_end_time_not_null[guid_col]
            end_time_values = subdf_end_time_not_null['combined'].values.tolist()
            for row_number, (stime_index, stime_row) in enumerate(subdf_start_time_not_null.iterrows()):
                delete_index = row_number
                if row_number < len(end_time_values):
                    end_time_value = np.nan
                    if int(str(subdf_start_time_not_null.at[stime_index,start_time_col]).replace(":","").replace(" ","").replace("-","")) <= int(str(end_time_values[row_number]).split("__")[0].replace(":","").replace(" ","").replace("-","")):
                        end_time_value = end_time_values[row_number]
                        subdf_start_time_not_null.at[stime_index,end_time_col] = str(end_time_values[row_number]).split("__")[0]
                    else:
                        prev_index = end_time_values.index(end_time_values[row_number])
                        for end_time in end_time_values:
                            current_index = end_time_values.index(end_time)
                            if current_index > prev_index:
                                if int(str(subdf_start_time_not_null.at[stime_index,start_time_col]).replace(":","").replace(" ","").replace("-","")) <= int(str(end_time_values[current_index]).split("__")[0].replace(":","").replace(" ","").replace("-","")):
                                    subdf_start_time_not_null.at[stime_index, end_time_col] = end_time_values[current_index]
                                    delete_index = current_index
                                    end_time_value = end_time_values.pop(delete_index)
                                    break
                    subdf_end_time_not_null = subdf_end_time_not_null[subdf_end_time_not_null[guid_col]!=end_time_value.split("__")[1]]
                else:
                    subdf_start_time_not_null.at[stime_index,end_time_col] = subdf_start_time_not_null.at[stime_index,start_time_col]
            subdf_end_time_not_null.drop('combined', axis=1, inplace=True)
            sub_df = pd.concat([subdf_start_time_not_null,subdf_end_time_not_null])
        sub_df[start_time_col] = np.where(sub_df[start_time_col].isnull(),sub_df[end_time_col],sub_df[start_time_col])
        sub_df[end_time_col] = np.where(sub_df[end_time_col].isnull(),sub_df[start_time_col],sub_df[end_time_col])
        final_dfs.append(sub_df)
        # LOGGER.info('do something' +str(index))
    df = pd.concat(final_dfs)
    context['data'] = df
    context['continue'] = True
    return context

其中参数如下：

param = {"keys_cols":['id', 'url'], "start_time_col":"start_time","end_time_col":"end_time"}

“df”是数据。

请帮助查看并建议如何使其更优化，我有超过 70000 行数据，一个文件中有超过 12000 对 id 和 urls

期待你们。

谢谢

Answer 1

数据：

>>> import pandas as pd
>>> df = pd.DataFrame(
    {"id" : ["o6FlbuA_5565423"]*8,
     "url" : ["https://vaa.66new"]*8,
     "type" : ["out"]*3 + ["in"]*2 + ["out"]*3,
     "start_time" : ["NULL"]*3 + ['2021-08-25 15:23:37', '2021-08-25 15:23:56'] +["NULL"]*3,
     "end_time" : ['2021-08-25 15:23:28', '2021-08-25 15:27:34', '2021-08-25 15:23:52', 'NULL', 'NULL', '2021-08-25 15:10:29', '2021-08-25 15:25:00', '2021-08-25 15:15:49']}
     )
>>> df[['start_time', 'end_time']] = df[['start_time', 'end_time']].apply(pd.to_datetime, errors='coerce')
>>> df

    id                  url                 type    start_time              end_time
0   o6FlbuA_5565423     https://vaa.66new   out     NaT                     2021-08-25 15:23:28
1   o6FlbuA_5565423     https://vaa.66new   out     NaT                     2021-08-25 15:27:34
2   o6FlbuA_5565423     https://vaa.66new   out     NaT                     2021-08-25 15:23:52
3   o6FlbuA_5565423     https://vaa.66new   in      2021-08-25 15:23:37     NaT
4   o6FlbuA_5565423     https://vaa.66new   in      2021-08-25 15:23:56     NaT
5   o6FlbuA_5565423     https://vaa.66new   out     NaT                     2021-08-25 15:10:29
6   o6FlbuA_5565423     https://vaa.66new   out     NaT                     2021-08-25 15:25:00
7   o6FlbuA_5565423     https://vaa.66new   out     NaT                     2021-08-25 15:15:49

解决方案：

# Get epoch time for both 'start_time' and 'end_time' columns
>>> df['start_time_epoch'] = df.start_time.apply(lambda x: x.timestamp() if not pd.isna(x) else None).astype('Int64')
>>> df['end_time_epoch'] = df.end_time.apply(lambda x: x.timestamp() if not pd.isna(x) else None).astype('Int64')

# Get closest value
>>> to_remove = []
>>> def fun(x):
>>>     for i in df.sort_values("end_time_epoch").end_time_epoch:
>>>         if i >= x.start_time_epoch:
>>>             to_remove.append(i)
>>>             return pd.to_datetime(i, unit='s')
>>>     else:
>>>         return pd.to_datetime(x.start_time_epoch, unit='s')
>>> r = df[df.start_time.notna() & df.end_time.isna()].apply(fun, axis=1).to_list()

# Fill with gotten values
>>> df.loc[df.start_time.notna() & df.end_time.isna(), 'end_time'] = r

# Remove rows from where we filled missed values.
>>> df = df[~df.end_time_epoch.isin(to_remove)]

# Fill 'start_time' with 'end_time'
>>> df.loc[df.start_time.isna(), 'start_time'] = df.loc[df.start_time.isna(), 'end_time'].to_list()

# Drop helping variables.
>>> df.drop(["start_time_epoch", "end_time_epoch"], axis=1, inplace=True)

>>> df

    id                  url                 type    start_time              end_time
0   o6FlbuA_5565423     https://vaa.66new   out     2021-08-25 15:23:28     2021-08-25 15:23:28
1   o6FlbuA_5565423     https://vaa.66new   out     2021-08-25 15:27:34     2021-08-25 15:27:34
3   o6FlbuA_5565423     https://vaa.66new   in      2021-08-25 15:23:37     2021-08-25 15:23:52
4   o6FlbuA_5565423     https://vaa.66new   in      2021-08-25 15:23:56     2021-08-25 15:25:00
5   o6FlbuA_5565423     https://vaa.66new   out     2021-08-25 15:10:29     2021-08-25 15:10:29
7   o6FlbuA_5565423     https://vaa.66new   out     2021-08-25 15:15:49     2021-08-25 15:15:49

Answer 2

如果我正确理解要求，我们可以在 pandas 内完成所有这些。这里基本上有两个步骤：

使用pandas.merge_asof填写最近的end_date
使用 drop_duplicates 删除我们在步骤 1 中使用的 out 条记录

text = StringIO(
    """
             id                url type          start_time            end_time
o6FlbuA_5565423  https://vaa.66new  out                 NaT 2021-08-25T15:23:28
o6FlbuA_5565423  https://vaa.66new  out                 NaT 2021-08-25T15:27:34
o6FlbuA_5565423  https://vaa.66new  out                 NaT 2021-08-25T15:23:52
o6FlbuA_5565423  https://vaa.66new   in 2021-08-25T15:23:37                 NaT
o6FlbuA_5565423  https://vaa.66new   in 2021-08-25T15:43:56                 NaT  # note: no record with `end_time` after this records `start_time`
o6FlbuA_5565423  https://vaa.66new  out                 NaT 2021-08-25T15:10:29
o6FlbuA_5565423  https://vaa.66new  out                 NaT 2021-08-25T15:25:00
o6FlbuA_5565423  https://vaa.66new  out                 NaT 2021-08-25T15:15:49
o6FlbuA_5565423  https://vaa.66new   in 2021-08-25T15:33:37 2021-08-25T15:34:37  # additional already complete record
"""
)
df = pd.read_csv(text, delim_whitespace=True, parse_dates=["start_time", "end_time"], comment="#")

# separate out unmatched `in` records and unmatched `out` records
df_in_unmatched = (
    df[(df.type == "in") & ~df.start_time.isna() & df.end_time.isna()]
    .drop(columns=["end_time"])
    .sort_values("start_time")
)
df_out_unmatched = (
    df[(df.type == "out") & df.start_time.isna() & ~df.end_time.isna()]
    .drop(columns=["type", "start_time"])
    .sort_values("end_time")
)

# match `in` records to closest `out` record with `out.end_time` >= `in.start_time`
df_in_matched = pd.merge_asof(
    df_in_unmatched,
    df_out_unmatched,
    by=["id", "url"],
    left_on="start_time",
    right_on="end_time",
    direction="forward",
    allow_exact_matches=True,
)

# fill in missing `end_time` for records with only `start_time`
df_in_matched["end_time"] = df_in_matched["end_time"].combine_first(
    df_in_matched["start_time"]
)

# combine matched records with remaining unmatched and deduplicate
# in order to remove "used" records
df_matched = (
    pd.concat([df_in_matched, df_out_unmatched], ignore_index=True)
    .drop_duplicates(subset=["id", "url", "end_time"], keep="first")
    .dropna(subset=["end_time"])
    .fillna({"type": "out"})
)

# fill in missing `start_time` for records with only `end_time`
df_matched["start_time"] = df_matched["start_time"].combine_first(
    df_matched["end_time"]
)

# combine matched records with unprocessed records: i.e. records
# that had both `start_time` and `end_time` (if extant)
df_final = pd.concat(
    [df_matched, df.dropna(subset=["start_time", "end_time"])], ignore_index=True
)

结果：

               id               url type         start_time             end_time
0 o6FlbuA_5565423 https://vaa.66new   in 2021-08-25 15:23:37 2021-08-25 15:23:52
1 o6FlbuA_5565423 https://vaa.66new   in 2021-08-25 15:43:56 2021-08-25 15:43:56
2 o6FlbuA_5565423 https://vaa.66new  out 2021-08-25 15:10:29 2021-08-25 15:10:29
3 o6FlbuA_5565423 https://vaa.66new  out 2021-08-25 15:15:49 2021-08-25 15:15:49
4 o6FlbuA_5565423 https://vaa.66new  out 2021-08-25 15:23:28 2021-08-25 15:23:28
5 o6FlbuA_5565423 https://vaa.66new  out 2021-08-25 15:25:00 2021-08-25 15:25:00
6 o6FlbuA_5565423 https://vaa.66new  out 2021-08-25 15:27:34 2021-08-25 15:27:34
7 o6FlbuA_5565423 https://vaa.66new   in 2021-08-25 15:33:37 2021-08-25 15:34:37

pandas 根据条件合并行

pandas combine rows based on conditions

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pandas-groupby

rows