# Split 2 last columns and assign index.
df_tmp = df[['CAS NO(2)', 'Value(2)']]
df_tmp = df_tmp.set_index('CAS NO(2)')
# Keep only 3 first columns of original dataframe
df = df[['Analyte',' CASNo(1)', 'Value(1)']]
# Now copy the CasNO(1) to CAS NO(2)
df['CAS NO(2)'] = df['CasNO(1)']
# Now create Value(2) column on original dataframe
df['Value(2)'] = df['CASNo(1)'].map(df_tmp.to_dict()['Value(2)'])
import pandas as pd
import numpy as np
#create an example of your table
list_CASNo1 = ['71-43-2', '100-41-4', np.nan, '1634-04-4']
list_Val1 = [np.nan]*len(list_CASNo1)
list_CASNo2 = [np.nan, np.nan, np.nan, '100-41-4']
list_Val2 = [np.nan, np.nan, np.nan, '18']
df = pd.DataFrame(zip(list_CASNo1, list_Val1, list_CASNo2, list_Val2), columns =['CASNo(1)','Value(1)','CAS NO(2)','Value(2)'], index = ['Benzene','Ethylbenzene','Gasonline Range Organics','Methyl-tert-butyl ether'])
#split the data to two dataframes
df1 = df[['CASNo(1)','Value(1)']]
df2 = df[['CAS NO(2)','Value(2)']]
#merge df2 to df1 based on the specified columns
#reset_index and set_index will take care
#that df_adjusted will have the same index names as df1
df_adjusted = df1.reset_index().merge(df2.dropna(),
how = 'left',
left_on = 'CASNo(1)',
right_on = 'CAS NO(2)').set_index('index')
最好以文本格式提供输入数据,以便我们可以复制粘贴它。我理解您这样的问题:您需要将最后两列排序在一起,以便CAS NO(2)与CAS NO(1)匹配
因为
CAS NO(2)=CAS(NO1)
所以不需要重复的CAS NO(2)
列,对吗拆分最后两列并从中生成一个系列,然后将该系列转换为dict,并使用该dict映射新值
请尝试以下操作:
但是要小心列中的重复项,它们会导致合并失败
您可以通过将df变量重新指定为列表中索引的一部分来对列进行重新排序,该列表的条目就是所讨论的列名
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