关于python DataFrame的合并方法总结

df1=pd.DataFrame([[1,2,3],[2,3,4]],columns=['a','b','c'])
df2=pd.DataFrame([[2,3,4],[3,4,5]],columns=['a','b','c'])
df3=pd.DataFrame([[1,2,3],[2,3,4]],columns=['a','b','d'])

df1
   a  b  c
0  1  2  3
1  2  3  4
df2
   a  b  c
0  2  3  4
1  3  4  5
df3
   a  b  d
0  1  2  3
1  2  3  4

pandas.concat(objs, axis=0, join='outer', join_axes=None, ignore_index=False,
           keys=None, levels=None, names=None, verify_integrity=False,
           copy=True)

pd.concat([df1,df2],axis=1)
   a  b  c  a  b  c
0  1  2  3  2  3  4
1  2  3  4  3  4  5

pd.concat([df2,df3],axis=0,join='inner')
   a  b
0  2  3
1  3  4
0  1  2
1  2  3
pd.concat([df2,df3],axis=1,join='inner')
   a  b  c  a  b  d
0  2  3  4  1  2  3
1  3  4  5  2  3  4

pd.concat([df1,df2],ignore_index=True)
   a  b  c
0  1  2  3
1  2  3  4
2  2  3  4
3  3  4  5

pandas.merge(left, right, how='inner', on=None, left_on=None, right_on=None,
          left_index=False, right_index=False, sort=False,
          suffixes=('_x', '_y'), copy=True, indicator=False,
          validate=None):

df_merge =df1.merge(df3,on=['a','b'])
   a  b  c  d
0  1  2  3  3
1  2  3  4  4

df1.append(self, other, ignore_index=False, verify_integrity=False)

df1.append(df2)
   a  b  c
0  1  2  3
1  2  3  4
0  2  3  4
1  3  4  5

result = pd.merge(对象1, 对象2, on='key')

result = df1.append(df2)
result = df1.append([df2, df3])
result = df1.append(df4, ignore_index=True)

result = left.join(right, on=['key1', 'key2'], how='inner')

pd.concat(objs, axis=0, join='outer', join_axes=None, ignore_index=False,
     keys=None, levels=None, names=None, verify_integrity=False,
     copy=True)
frames = [df1, df2, df3]
result = pd.concat(frames)
result = pd.concat(frames, keys=['x', 'y', 'z'])
result = pd.concat([df1, df4], ignore_index=True)