pandas 熊猫合并返回空数据框
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Pandas merge return empty dataframe
提问by Daniel
I have two dataframes
我有两个数据框
current_bin.info()
<class 'pandas.core.frame.DataFrame'>
Int64Index: 16 entries, 0 to 15
Data columns (total 3 columns):
id 16 non-null object
fpd 16 non-null float64
avgSpeedBinID 16 non-null object
dtypes: float64(1), object(2)
the current_bin data frame looks like:
current_bin 数据框如下所示：
current_bin
id fpd avgSpeedBinID
0 1.1.4.1 2.818623 1
1 1.1.4.10 0.266681 10
2 1.1.4.11 0.250017 11
3 1.1.4.12 0.234749 12
4 1.1.4.13 0.222515 13
5 1.1.4.14 0.216150 14
6 1.1.4.15 0.218368 15
7 1.1.4.16 0.227663 16
8 1.1.4.2 1.475454 2
9 1.1.4.3 0.805842 3
10 1.1.4.4 0.581797 4
11 1.1.4.5 0.450314 5
12 1.1.4.6 0.379107 6
13 1.1.4.7 0.335155 7
14 1.1.4.8 0.305992 8
15 1.1.4.9 0.284210 9
and
和
avg.info()
<class 'pandas.core.frame.DataFrame'>
Int64Index: 16 entries, 0 to 15
Data columns (total 4 columns):
avgSpeedBinID 16 non-null int64
avgBinSpeed 16 non-null float64
avgSpeedBinDesc 16 non-null object
temp 16 non-null int64
dtypes: float64(1), int64(2), object(1)
which looks like:
看起来像：
avgSpeedBinID avgBinSpeed avgSpeedBinDesc temp
0 1 3 speed < 2.5mph 0
1 2 5 2.5mph <= speed < 7.5mph 0
2 3 10 7.5mph <= speed < 12.5mph 0
3 4 15 12.5mph <= speed < 17.5mph 0
4 5 20 17.5mph <= speed <22.5mph 0
5 6 25 22.5mph <= speed < 27.5mph 0
6 7 30 27.5mph <= speed < 32.5mph 0
7 8 35 32.5mph <= speed < 37.5mph 0
8 9 40 37.5mph <= speed < 42.5mph 0
9 10 45 42.5mph <= speed < 47.5mph 0
10 11 50 47.5mph <= speed < 52.5mph 0
11 12 55 52.5mph <= speed < 57.5mph 0
12 13 60 57.5mph <= speed < 62.5mph 0
13 14 65 62.5mph <= speed < 67.5mph 0
14 15 70 67.5mph <= speed < 72.5mph 0
15 16 75 72.5mph <= speed 0
both dataframes have a value 1 to 16 on the avgSpeedBinID field, however, when i try to merge the data frames together
两个数据帧在 avgSpeedBinID 字段上的值都为 1 到 16，但是，当我尝试将数据帧合并在一起时
avg.merge(current_bin, on='avgSpeedBinID')
I'm getting a null dataframe
我得到一个空数据框
avgSpeedBinID avgBinSpeed avgSpeedBinDesc temp id fpd
Why is this happening and how can i correct the problem?
为什么会发生这种情况，我该如何解决问题？
回答by Daniel
The avgSpeedBinIDin the current bin dataframe is type strand in avg is int.
Just cast the strone into an intand the merge will work.
在avgSpeedBinID当前斌数据帧的类型str和平均是int。只需将str一个转换为 an int，合并就会起作用。
current_bin['avgSpeedBinID'] = current_bin['avgSpeedBinID'].astype(int)
avg.merge(current_bin, on='avgSpeedBinID')
avgSpeedBinID avgBinSpeed avgSpeedBinDesc temp id fpd
0 1 3 speed < 2.5mph 0 1.1.4.1 2.818623
1 2 5 2.5mph <= speed < 7.5mph 0 1.1.4.2 1.475454
2 3 10 7.5mph <= speed < 12.5mph 0 1.1.4.3 0.805842
3 4 15 12.5mph <= speed < 17.5mph 0 1.1.4.4 0.581797
4 5 20 17.5mph <= speed <22.5mph 0 1.1.4.5 0.450314
5 6 25 22.5mph <= speed < 27.5mph 0 1.1.4.6 0.379107
6 7 30 27.5mph <= speed < 32.5mph 0 1.1.4.7 0.335155
7 8 35 32.5mph <= speed < 37.5mph 0 1.1.4.8 0.305992
8 9 40 37.5mph <= speed < 42.5mph 0 1.1.4.9 0.284210
9 10 45 42.5mph <= speed < 47.5mph 0 1.1.4.10 0.266681
10 11 50 47.5mph <= speed < 52.5mph 0 1.1.4.11 0.250017
11 12 55 52.5mph <= speed < 57.5mph 0 1.1.4.12 0.234749
12 13 60 57.5mph <= speed < 62.5mph 0 1.1.4.13 0.222515
13 14 65 62.5mph <= speed < 67.5mph 0 1.1.4.14 0.216150
14 15 70 67.5mph <= speed < 72.5mph 0 1.1.4.15 0.218368
15 16 75 72.5mph <= speed 0 1.1.4.16 0.22763
