gistfile1.py

import os                                                                        
import urllib                                                                    
from ftplib import FTP                                                           
import socket                                                                   
 
from pupynere import netcdf_file                                                
                                                                                 
                                                                                 
class FTPFile(object):                                                           
    def __init__(self, url, buffer=4096):                                        
        protocol, location = url.split('://', 1)                                 
        auth, host = urllib.splituser(location)                                  
        if auth:                                                                 
            username, password = urllib.splitpasswd(auth)                        
        else:                                                                    
            username = password = None                                           
        host, filepath = urllib.splithost('//' + host)                           
        path, self.filename = os.path.split(filepath)                            
                                                                                 
        self.ftp = FTP(host, username, password)                                 
        self.ftp.set_debuglevel(2)                                               
        self.ftp.login()                                                         
        self.ftp.sendcmd("TYPE i")                                               
        self.ftp.cwd(path)                                                       
                                                                                 
        self.buffer = buffer                                                     
        self.position = 0                                                        
        self.closed = False                                                      
                                                                                 
    def tell(self):                                                              
        return self.position                                                     
                                                                                 
    def seek(self, position):                                                    
        self.position = position                                                 
                                                                                 
    def read(self, count):                                                       
        offset = self.position                                                   
        self.position += count                                                   
                                                                                 
        # start reading from offset                                              
        s = self.ftp.transfercmd("RETR " + self.filename, offset)                
        try:                                                                     
            data = ''                                                            
            while True:                                                          
                chunk = s.recv(self.buffer)                                      
                if not chunk or len(data) >= count:                              
                    break                                                        
                data += chunk                                                    
        except socket.timeout:                                                   
            raise Exception                                                      
                                                                                 
        return data[:count]                                                      
                                                                                 
    def close(self):                                                             
        self.closed = True 


buf = FTPFile('ftp://user:password@host/path/to/file.nc')
f = netcdf_file(buf)  
print f.variables