熊猫数据框应用功能中的异常

Question

I am getting the following error and I am not sure what it is. Can you please help me identify what is causing this error?

def determine_device_type(*args, **kwargs):
    device_name = str(args[0])
    #print(device_name)
    if re.search(r'^\w+c(\d\d|\w\w|\d\d\d\d)$', device_name):
        print(device_name, ' --> ', 'Cisco')
        return 'Cisco'
    if re.search(r'^\w+r(\d\d|\w\w|\d\d\d\d)$', device_name):
        print(device_name, ' --> ', 'Riverbed')
        return 'Riverbed'
    if re.search(r'^\w+j(\d\d|\w\w|\d\d\d\d)$', device_name):
        print(device_name, ' --> ', 'Juniper')
        return 'Juniper'

    return ''

vendor = df['DEVICE'].apply(determine_device_type)  
df.insert(3, 'VENDOR', vendor) 

Error

    ValueError                                Traceback (most recent call last)
<ipython-input-42-8b32a12d4761> in <module>()
     21 
     22 vendor = df['MDN_DEVICE'].apply(determine_device_type)
---> 23 df.insert(3, 'VENDOR', vendor)
     24 df

C:\Continuum\anaconda3\lib\site-packages\pandas\core\frame.py in insert(self, loc, column, value, allow_duplicates)
   2611         value = self._sanitize_column(column, value, broadcast=False)
   2612         self._data.insert(loc, column, value,
-> 2613                           allow_duplicates=allow_duplicates)
   2614 
   2615     def assign(self, **kwargs):

C:\Continuum\anaconda3\lib\site-packages\pandas\core\internals.py in insert(self, loc, item, value, allow_duplicates)
   4061         if not allow_duplicates and item in self.items:
   4062             # Should this be a different kind of error??
-> 4063             raise ValueError('cannot insert {}, already exists'.format(item))
   4064 
   4065         if not isinstance(loc, int):

ValueError: cannot insert VENDOR, already exists

Answer 1

It seems you already have a 'VENDOR' column. You can use the df.head() to confirm. To avoid the error, drop the column before inserting.

df.drop(columns=['VENDOR']).insert(3, 'VENDOR', vendor)