应用函数中的动态数据帧列名称

时间:2018-02-05 18:34:39

标签: python pandas

我正在使用当前的数据框:

df = pd.DataFrame({'columnA':[1111,1111,2222,3333,4444,4444,5555,6666],
                   'columnB':['AAAA','AAAA','BBBB','AAAA','BBBB','BBBB','AAAA','BBBB'],
                   'columnC':['one','two','one','one','one','sales','two','one'],
                   'NUM1':[1,3,5,7,1,0,4,5],
                   'NUM2':[5,3,6,9,2,4,1,1],
                   'W':list('aaabbbbb')})

我试图在以下代码中使用动态列:

#First aggregate the data
d = {'columnB':'unique', 'columnC':'unique' }
df2 = df.groupby('columnA').agg(d)


#Convert list to string for each cell of the inventory field
mylist = ["columnB","columnC"]
for x in mylist:
    columnName = x
    #print("df2."+columnName+".apply(', '.join)")
    df2[columnName] = df2[columnName].apply(', '.join)

它在Jupyter中运行良好。我的问题是,当我在visualstudio上运行它时,它不起作用。我收到了这个错误:

  

序列项0:预期的str实例,浮点数

打印数据框的类型后,我得到了这个:

<class 'pandas.core.frame.DataFrame'>

以下是完整的错误消息:

  

回溯(最近一次呼叫最后一次):文件&#34; stage1.py&#34;,第112行,在main()文件&#34; stage1.py&#34;,第57行,在主模板方案[columnName] ] = templateScenarios [columnName] .apply(&#39;,&#39; .join)File&#34; /Users/apolo.siskos/anaconda3/lib/python3.6/site-packages/pandas/core/series .py&#34;,第2355行,在pandas._libs中应用mapped = lib.map_infer(values,f,convert = convert_dtype)文件&#34; pandas / _libs / src / inference.pyx&#34;,第1574行.lib.map_infer TypeError:sequence item 0:expect str instance,float found

1 个答案:

答案 0 :(得分:1)

存在问题NaN的值,因此可以dropna删除它们并使用自定义函数join

df = pd.DataFrame({'columnA':[1111,1111,2222,3333,4444,4444,5555,6666],
                   'columnB':[np.nan,np.nan,'BBBB','AAAA','BBBB','BBBB','AAAA','BBBB'],
                   'columnC':['one','two','one','one','one','sales','two','one'],
                   'NUM1':[1,3,5,7,1,0,4,5],
                   'NUM2':[5,3,6,9,2,4,1,1],
                   'W':list('aaabbbbb')})

f = lambda x: ', '.join(x.dropna().unique())
d = {'columnB': f, 'columnC':f}
df2 = df.groupby('columnA').agg(d)
print (df2)
        columnB     columnC
columnA                    
1111               one, two
2222       BBBB         one
3333       AAAA         one
4444       BBBB  one, sales
5555       AAAA         two
6666       BBBB         one