从列表和字典的组合创建熊猫数据框答案

【问题标题】：Create pandas dataframe from the combination of list and dictionary从列表和字典的组合创建熊猫数据框
【发布时间】：2022-01-11 18:09:16
【问题描述】：

col = ['c1_1', 'c1_2', 'c1_3', 'c1$1']
d = {4:'improvement needed',5:'very bad'}

如何使用pd.DataFrame（pandas库）得到如上图的输出

【问题讨论】：

与how='cross'合并。
感谢@QuangHoang。这是最聪明的方法。

标签： python python-3.x pandas dataframe numpy

【解决方案1】：

import pandas as pd

col = ['c1_1', 'c1_2', 'c1_3', 'c1$1']
# use list comprehension to duplicate each item in col list 
col = [col[i//2] for i in range(len(col)*2)]

d = {4:'improvement needed', 5:'very bad'}

df = pd.DataFrame({'final_col_name': col})
# duplicate each item in list of d keys
final_val_code = list(d.keys()) * int(df.shape[0] / 2) * int(df.shape[0] / 2)

df['final_val_code'] = final_val_code
# map d values to final_val_code col 
df['final_val_label'] = df['final_val_code'].map(d)

print(df) 

    final_col_name  final_val_code  final_val_label
0   c1_1            4               improvement needed
1   c1_1            5               very bad
2   c1_2            4               improvement needed
3   c1_2            5               very bad
4   c1_3            4               improvement needed
5   c1_3            5               very bad
6   c1$1            4               improvement needed
7   c1$1            5               very bad

【讨论】：

【解决方案2】：

感谢 Quang 的评论。最熊猫的做法会是这样的：

pd.DataFrame(col,columns=['final_col_name']).merge(pd.DataFrame(d.items(), columns=['final_val_code','final_val_label']),how = 'cross')

【讨论】：