python-3.x - Pandas 合并返回空数据框

Question

我正在从两个不同的 csv 加载两个数据帧，并尝试加入它们，但由于某种原因 pd.merge 没有加入数据并返回空数据帧。我尝试过更改数据类型，但仍然没有任何结果。感谢任何帮助。

示例 mon_apps 数据帧:

app_cnts | year | month
16634    | 2018    |  8 
9636     | 2019    |  2 
17402    | 2017    |  8 
17472    | 2017    |  11 
15689    | 2018    |  6 

示例mon_spend数据帧:

channel  | month   | year  | spend
FB       | 1       |  2017 | 0
FB       | 2       |  2017 | 0
FB       | 3       |  2017 | 0
FB       | 4       |  2017 | 0
FB       | 5       |  2017 | 0

我更改了数据类型(只是为了确保这不是问题)，如下所示:

mon_spend[['month', 'year', 'spend']] = mon_spend[['month', 'year', 'spend']].astype(np.int64)
mon_spend['channel'] = mon_spend['channel'].astype(str)
mon_apps = mon_apps.astype(np.int64)

我检查数据类型:

mon_spend
channel    object
month       int64
year        int64
spend       int64
dtype: object

mon_apps
app_cnts    int64
year        int64
month       int64
dtype: object

我使用 pd.merge 加入，如下所示:

pd.merge(mon_apps[['app_cnts', 'year', 'month']], mon_spend, left_on = ["year", "month"], right_on = ["year", "month"])

感谢任何帮助。谢谢。

更多数据

channel month year spend




FB 2017 1 0 


FB 2017 2 0 


FB 2017 3 0 


FB 2017 4 0 


FB 2017 5 0 


FB 2017 6 0 


FB 2017 7 52514 


FB 2017 8 10198 


FB 2017 9 25408 


FB 2017 10 31333 


FB 2017 11 128071 


FB 2017 12 95160 


FB 2018 1 5001 


FB 2018 2 17929 


FB 2018 3 84548 


FB 2018 4 16414 


FB 2018 5 28282 


FB 2018 6 38430 


FB 2018 7 58757 


FB 2018 8 120722 


FB 2018 9 143766 


FB 2018 10 68400 


FB 2018 11 66984 


FB 2018 12 58228 

更多信息

print (mon_spend[["year", "month"]].sort_values(["year", "month"]).drop_duplicates().values.tolist())
[[2017, 1], [2017, 2], [2017, 3], [2017, 4], [2017, 5]]
​
print (mon_apps[["year", "month"]].sort_values(["year", "month"]).drop_duplicates().values.tolist())

[[2017, 8], [2017, 11], [2018, 6], [2018, 8], [2019, 2]]









[[1, 2017], [1, 2018], [1, 2019], [2, 2017], [2, 2018], [2, 2019], [3, 2017], [3, 2018], [4, 2017], [4, 2018], [5, 2017], [5, 2018], [6, 2017], [6, 2018], [7, 2017], [7, 2018], [8, 2017], [8, 2018], [9, 2017], [9, 2018], [10, 2017], [10, 2018], [11, 2017], [11, 2018], [12, 2017], [12, 2018]]
[[2017, 1], [2017, 2], [2017, 3], [2017, 4], [2017, 5], [2017, 6], [2017, 7], [2017, 8], [2017, 9], [2017, 10], [2017, 11], [2017, 12], [2018, 1], [2018, 2], [2018, 3], [2018, 4], [2018, 5], [2018, 6], [2018, 7], [2018, 8], [2018, 9], [2018, 10], [2018, 11], [2018, 12], [2019, 1], [2019, 2], [2019, 3]]




Out[18]:

[[2017, 8], [2017, 11], [2018, 6], [2018, 8], [2019, 2]]

Answer 1

您要合并的文件中的月份和年份会交换，请尝试在合并时交换键或在合并之前重命名它们:

mon_apps.merge(complete_file, left_on=["year", "month"],right_on=['month','year'])