如果你有3个数据框架，你可以试试这个

# Merge multiple dataframes
df1 = pd.DataFrame(np.array([
    ['a', 5, 9],
    ['b', 4, 61],
    ['c', 24, 9]]),
    columns=['name', 'attr11', 'attr12'])
df2 = pd.DataFrame(np.array([
    ['a', 5, 19],
    ['b', 14, 16],
    ['c', 4, 9]]),
    columns=['name', 'attr21', 'attr22'])
df3 = pd.DataFrame(np.array([
    ['a', 15, 49],
    ['b', 4, 36],
    ['c', 14, 9]]),
    columns=['name', 'attr31', 'attr32'])

pd.merge(pd.merge(df1,df2,on='name'),df3,on='name')

或者，正如考兰德提到的

df1.merge(df2,on='name').merge(df3,on='name')

对于一个数据帧列表df_list，也可以这样做:

df = df_list[0]
for df_ in df_list[1:]:
    df = df.merge(df_, on='join_col_name')

或者如果数据帧在生成器对象中(例如，为了减少内存消耗):

df = next(df_list)
for df_ in df_list:
    df = df.merge(df_, on='join_col_name')

可以使用.join()函数将三者连接在一起。

假设你有三个数据框架 Df1 df2 df3。 要将这些数据加入到一个数据框架中，你可以:

df = df1.join(df2).join(df3)

这是我发现的完成这项任务最简单的方法。

如果你有3个数据框架，你可以试试这个

# Merge multiple dataframes
df1 = pd.DataFrame(np.array([
    ['a', 5, 9],
    ['b', 4, 61],
    ['c', 24, 9]]),
    columns=['name', 'attr11', 'attr12'])
df2 = pd.DataFrame(np.array([
    ['a', 5, 19],
    ['b', 14, 16],
    ['c', 4, 9]]),
    columns=['name', 'attr21', 'attr22'])
df3 = pd.DataFrame(np.array([
    ['a', 15, 49],
    ['b', 4, 36],
    ['c', 14, 9]]),
    columns=['name', 'attr31', 'attr32'])

pd.merge(pd.merge(df1,df2,on='name'),df3,on='name')

或者，正如考兰德提到的

df1.merge(df2,on='name').merge(df3,on='name')

df1 = pd.DataFrame(np.array([
    ['a', 5, 9],
    ['b', 4, 61],
    ['c', 24, 9]]),
    columns=['name', 'attr11', 'attr12']
)
df2 = pd.DataFrame(np.array([
    ['a', 5, 19],
    ['d', 14, 16]]

),
    columns=['name', 'attr21', 'attr22']
)
df3 = pd.DataFrame(np.array([
    ['a', 15, 49],
    ['c', 4, 36],
    ['d', 14, 9]]),
    columns=['name', 'attr31', 'attr32']
)
df4 = pd.DataFrame(np.array([
    ['a', 15, 49],
    ['c', 4, 36],
    ['c', 14, 9]]),
    columns=['name', 'attr41', 'attr42']
)

加入列表数据框架的三种方法

pandas.concat

dfs = [df1, df2, df3]
dfs = [df.set_index('name') for df in dfs]
# cant not run if index not unique 
dfs = pd.concat(dfs, join='outer', axis = 1) 

functools.reduce

dfs = [df1, df2, df3, df4]
# still run with index not unique 
import functools as ft
df_final = ft.reduce(lambda left, right: pd.merge(left, right, on='name', how = 'outer'), dfs)

加入

# cant not run if index not unique 
dfs = [df1, df2, df3]
dfs = [df.set_index('name') for df in dfs]
dfs[0].join(dfs[1:], how = 'outer')

不需要多索引来执行连接操作。 我们只需要正确地设置索引列来执行连接操作(例如哪个命令df.set_index('Name'))

默认情况下，连接操作在索引上执行。 在本例中，只需指定Name列对应于索引。 下面是一个例子

教程可能会有用。

# Simple example where dataframes index are the name on which to perform
# the join operations
import pandas as pd
import numpy as np
name = ['Sophia' ,'Emma' ,'Isabella' ,'Olivia' ,'Ava' ,'Emily' ,'Abigail' ,'Mia']
df1 = pd.DataFrame(np.random.randn(8, 3), columns=['A','B','C'], index=name)
df2 = pd.DataFrame(np.random.randn(8, 1), columns=['D'],         index=name)
df3 = pd.DataFrame(np.random.randn(8, 2), columns=['E','F'],     index=name)
df = df1.join(df2)
df = df.join(df3)

# If you have a 'Name' column that is not the index of your dataframe,
# one can set this column to be the index
# 1) Create a column 'Name' based on the previous index
df1['Name'] = df1.index
# 1) Select the index from column 'Name'
df1 = df1.set_index('Name')

# If indexes are different, one may have to play with parameter how
gf1 = pd.DataFrame(np.random.randn(8, 3), columns=['A','B','C'], index=range(8))
gf2 = pd.DataFrame(np.random.randn(8, 1), columns=['D'], index=range(2,10))
gf3 = pd.DataFrame(np.random.randn(8, 2), columns=['E','F'], index=range(4,12))

gf = gf1.join(gf2, how='outer')
gf = gf.join(gf3, how='outer')