pandasの定点挿入列

# coding: utf-8

# In[1]:


import pandas as pd
import numpy as np


# In[2]:


a = np.random.randint(1, 6, (5, 3))


# In[3]:


b = pd.DataFrame(a, columns=['A', 'B', 'C'])


# - ###     

# In[4]:


b['col_add'] = np.nan  


# In[5]:


b.head()


# - ###       

#    - ######       

# In[6]:


w = b.loc[:, ['A', 'col_add', 'B', 'C']]


# In[7]:


w


#    - ######   2   

# In[8]:


col_origin = list(b.columns[: -1])
col_insert = b.columns[-1]


# In[9]:


col_origin.insert(1, col_insert)#col_inserted = col_origin.insert(1, col_insert)      ， insert     


# In[10]:


col_origin


# In[11]:


ww = b.loc[:, col_origin]                 


# In[12]:


ww