大 pandas :在多列上合并(合并)两个数据框 [英] pandas: merge (join) two data frames on multiple columns
问题描述
我正在尝试使用两列来连接两个熊猫数据框:
I am trying to join two pandas data frames using two columns:
new_df = pd.merge(A_df, B_df, how='left', left_on='[A_c1,c2]', right_on = '[B_c1,c2]')
但出现以下错误:
pandas/index.pyx in pandas.index.IndexEngine.get_loc (pandas/index.c:4164)()
pandas/index.pyx in pandas.index.IndexEngine.get_loc (pandas/index.c:4028)()
pandas/src/hashtable_class_helper.pxi in pandas.hashtable.PyObjectHashTable.get_item (pandas/hashtable.c:13166)()
pandas/src/hashtable_class_helper.pxi in pandas.hashtable.PyObjectHashTable.get_item (pandas/hashtable.c:13120)()
KeyError: '[B_1, c2]'
任何想法都应该是正确的方法吗?谢谢!
Any idea what should be the right way to do this? Thanks!
推荐答案
尝试一下
new_df = pd.merge(A_df, B_df, how='left', left_on=['A_c1','c2'], right_on = ['B_c1','c2'])
http://pandas. pydata.org/pandas-docs/version/0.19.1/generated/pandas.DataFrame.merge.html
left_on:标签或列表,或类似数组的字段名称,要在左侧加入 数据框.可以是长度为的向量或向量列表 DataFrame使用特定向量作为连接键,而不是 列
left_on : label or list, or array-like Field names to join on in left DataFrame. Can be a vector or list of vectors of the length of the DataFrame to use a particular vector as the join key instead of columns
right_on:要加入的标签或列表,或类似数组的字段名称 在右边的DataFrame或每个left_on docs的向量/向量列表中
right_on : label or list, or array-like Field names to join on in right DataFrame or vector/list of vectors per left_on docs
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