Question

I have a data table in a python list and the data looks like this:

[    
{Artist='Madonna', album='Ray of Light', title='Substitute for love'},    
{Artist='Madonna', album='Ray of Light', title='Frozen'},    
{Artist='Madonna', album='Something to remember', title='You'll see'},    
{Artist='Madonna', album='Bedtime stories', title='Secret'},    
{Artist='U2', album='The Joshua Tree', title='Where the streets have no name'}, 
{Artist='U2', album='The Joshua Tree', title='I still haven'ts found...'},    
{Artist='U2', album='The Joshua Tree', title='With or without you'},    
{Artist='U2', album='Acthung Baby', title='One'},    
{Artist='U2', album='Acthung Baby', title='Until the end of the world'}    
]

and I want to put it into a tree view (specifically, a QTreeWidget), so that it looks like this:

• Madonna
  • Ray of Light
    • Substitute for love
    • Frozen
  • Something to remember
    • You’ll see
  • Bedtime stories
    • Secret
• U2
  • The Joshua Tree
    • Where the streets..
    • I still haven’t…
  • Achtung baby
    • One
    • Until the end of..

I don’t know how to code it in this way: I think of nested loops but I can’t find a solution. Has anyone worked on a solution for this query, in any language please?
If not the code, I’ll need the logic. Then anyone could implement it using their own programming language.

Answer 1

You can turn the list of records into a nested dictionary using nested defaultdicts.

from collections import defaultdict

data = [ {'Artist':'Madonna', 'album':'Ray of Light', 'title':'Substitute for love'},
         ....
         {'Artist':'U2', 'album':'Acthung Baby', 'title':'Until the end of the world'}
      ]   

tree_data = defaultdict(lambda: defaultdict(list))

for d in data:
    tree_data[d['Artist']][d['album']].append(d['title'])

Once you have the data in this form, it’s easy to print it in the format you require.

Here’s a straightforward approach for your example:

for artist in tree_data.keys():
    print(artist)
    for album, titles in tree_data[artist].iteritems():
        print("\t" + album)
        for title in titles:
            print ("\t\t" + title)