字典/数据库键值检索

Question

As stated in a previous (but different) question, I'm trying to figure out a 'simple' dictionary/database with Python, which will retrieve a name from a list of ten, with the requested information. ie input could be 'John phone', where the output is 'John's phone number is 0401' (which I have down pat); but I could also input 'John Birthday' or 'John hobbies' and the output would correspond.

As I'm a complete noob, I'm not even sure where to start. Several hours of googling and poring over lecture notes have yielded nothing so far. I've got the feeling it's got something to do with the multiple argument % function but our lecturer really wasn't clear about how to take it further. So far, what I have is:

#!/usr/bin/python

friends = {'John': {'phone' : '0401',
                    'birthday' : '31 July',
                    'address' : 'UK',
                    'interests' : ['a', 'b', 'c']},
           'Harry': {'phone' : '0402',
                    'birthday' : '2 August',
                    'address' : 'Hungary',
                    'interests' : ['d', 'e', 'f']}}
name = raw_input ('Please enter search criteria: ')
if name in friends: 
    print "%s's phone number is: %s" % (name, friends[name]['phone'])
else: 
    print 'no data'

I'd also like to use the 'while' function so the prog doesn't close as soon as that information is given, but not sure if this would be appropriate. Any pointers would be great, even if it's a 'try this' kind of hint, or a link to a relevant website.

Answer 1

Since this is homework, I'll limit my answer to some hints:

1. tok = name.split() would split name into a list of words, so 'John address' would become ['John', 'address'] .
2. You can access the individual words as tok[0] and tok[1] , and use them to index into friends to get the relevant person and then the relevant field.
3. I see no problem with wrapping the input/search logic into a while loop so that the user can perform multiple queries. The only thing to figure out is how you're going to exit that loop.

Answer 2

Based on your sample code, 'John phone' wouldn't work since it would actually be looking up 'John phone' as the name (and 'phone' is hardcoded). For illustration, try code like this:

response = raw_input('Please enter search criteria: ').split()

try:
    print "%s's %s is %s" % (response[0], response[1], friends[response[0]][response[1]])
except KeyError:
    print 'no data'

the split() takes each argument separately which can then be referenced with [0] and [1] (and so forth). You were already on the right track with % substitution, but this approach will give it more usability and readability.

The key is that you shouldn't need to check if the name matches (or the criteria matches). Assume it'll be there--and in the event of an exceptional case (that the matches aren't found), it can return 'no data' as expected.

Please enter search criteria: John phone
John's phone is 0401

Please enter search criteria: Harry birthday
Harry's birthday is 2 August

Answer 3

Listen to aix for the first part of your question. For the second part, I'd suggest coming up with an exit value (perhaps 'exit') that the user could type to leave the program, then have your while loop keep going while input is not that value.