这是join方法的理想情况

join方法正是为这些类型的情况构建的。你可以加入任意数量的数据框架。调用的DataFrame与传递的DataFrame集合的索引连接。要使用多个dataframe，必须将连接列放在索引中。

代码看起来像这样:

filenames = ['fn1', 'fn2', 'fn3', 'fn4',....]
dfs = [pd.read_csv(filename, index_col=index_col) for filename in filenames)]
dfs[0].join(dfs[1:])

使用@zero的数据，你可以这样做:

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'])

dfs = [df1, df2, df3]
dfs = [df.set_index('name') for df in dfs]
dfs[0].join(dfs[1:])

     attr11 attr12 attr21 attr22 attr31 attr32
name                                          
a         5      9      5     19     15     49
b         4     61     14     16      4     36
c        24      9      4      9     14      9

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')

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')

这是join方法的理想情况

join方法正是为这些类型的情况构建的。你可以加入任意数量的数据框架。调用的DataFrame与传递的DataFrame集合的索引连接。要使用多个dataframe，必须将连接列放在索引中。

代码看起来像这样:

filenames = ['fn1', 'fn2', 'fn3', 'fn4',....]
dfs = [pd.read_csv(filename, index_col=index_col) for filename in filenames)]
dfs[0].join(dfs[1:])

使用@zero的数据，你可以这样做:

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'])

dfs = [df1, df2, df3]
dfs = [df.set_index('name') for df in dfs]
dfs[0].join(dfs[1:])

     attr11 attr12 attr21 attr22 attr31 attr32
name                                          
a         5      9      5     19     15     49
b         4     61     14     16      4     36
c        24      9      4      9     14      9

在python 3.6.3和pandas 0.22.0中，你也可以使用concat，只要你将你想要用于连接的列设置为index:

pd.concat(
    objs=(iDF.set_index('name') for iDF in (df1, df2, df3)),
    axis=1, 
    join='inner'
).reset_index()

其中df1, df2和df3定义为John Galt的答案:

import pandas as pd
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']
)

我调整了接受的答案，使用reduce对不同后缀参数上的多个数据帧执行操作，我猜它也可以扩展到不同的参数上。

from functools import reduce 

dfs_with_suffixes = [(df2,suffix2), (df3,suffix3), 
                     (df4,suffix4)]

merge_one = lambda x,y,sfx:pd.merge(x,y,on=['col1','col2'..], suffixes=sfx)

merged = reduce(lambda left,right:merge_one(left,*right), dfs_with_suffixes, df1)