Arrange the list of list in python

Question

I have some input data format, its like a tree. and contains list of list of list. the input is like

in_put = [[['shop_id', '=', 1]],
           [['shop_id', '=', 1],['product_id', '=', 16]],
           [['shop_id', '=', 1],['product_id', '=', 8]],
           [['shop_id', '=', 1],['product_id', '=', 4]],
           [['shop_id', '=', 1],['product_id', '=', 6]],
           [['shop_id', '=', 1],['product_id', '=', 16],['so', '=', 1]],
           [['shop_id', '=', 1],['product_id', '=', 8],['so', '=', 1]],
           [['shop_id', '=', 1],['product_id', '=', 4],['so', '=', 1]],
           [['shop_id', '=', 1],['product_id', '=', 6],['so', '=', 1]],
           [['shop_id', '=', 1],['product_id', '=', 16],['so', '=', 2]],
           [['shop_id', '=', 1],['product_id', '=', 8],['so', '=', 2]],
           [['shop_id', '=', 1],['product_id', '=', 4],['so', '=', 2]],
           [['shop_id', '=', 1],['product_id', '=', 6],['so', '=', 2]],
           [['shop_id', '=', 1],['product_id', '=', 16],['so', '=', 1],['state', '=', u'draft']],
           [['shop_id', '=', 1],['product_id', '=', 8],['so', '=', 1],['state', '=', u'draft']],
           [['shop_id', '=', 1],['product_id', '=', 4],['so', '=', 1],['state', '=', u'draft']],
           [['shop_id', '=', 1],['product_id', '=', 6],['so', '=', 1],['state', '=', u'draft']],
           [['shop_id', '=', 1],['product_id', '=', 16],['so', '=', 2],['state', '=', u'draft']],
           [['shop_id', '=', 1],['product_id', '=', 8],['so', '=', 2],['state', '=', u'draft']],
           [['shop_id', '=', 1],['product_id', '=', 4],['so', '=', 2],['state', '=', u'draft']],
           [['shop_id', '=', 1],['product_id', '=', 6],['so', '=', 2],['state', '=', u'draft']],
           ]

and i wanted to arrange the data in below format.

output = [   
    [['shop_id', '=', 1]],
    [['shop_id', '=', 1],['product_id', '=', 16]],
    [['shop_id', '=', 1],['product_id', '=', 16],['so', '=', 1]],
    [['shop_id', '=', 1],['product_id', '=', 16],['so', '=', 2]],
    [['shop_id', '=', 1],['product_id', '=', 16],['so', '=', 1],['state', '=', u'draft']],
    [['shop_id', '=', 1],['product_id', '=', 16],['so', '=', 2],['state', '=', u'draft']],
    [['shop_id', '=', 1],['product_id', '=', 8]],
    [['shop_id', '=', 1],['product_id', '=', 8],['so', '=', 1]],
    [['shop_id', '=', 1],['product_id', '=', 8],['so', '=', 2]],
    [['shop_id', '=', 1],['product_id', '=', 8],['so', '=', 1],['state', '=', u'draft']],
    [['shop_id', '=', 1],['product_id', '=', 8],['so', '=', 2],['state', '=', u'draft']],
    [['shop_id', '=', 1],['product_id', '=', 4]],
    [['shop_id', '=', 1],['product_id', '=', 4],['so', '=', 1]],
    [['shop_id', '=', 1],['product_id', '=', 4],['so', '=', 2]],
    [['shop_id', '=', 1],['product_id', '=', 4],['so', '=', 1],['state', '=', u'draft']],
    [['shop_id', '=', 1],['product_id', '=', 4],['so', '=', 2],['state', '=', u'draft']],
    [['shop_id', '=', 1],['product_id', '=', 6]],
    [['shop_id', '=', 1],['product_id', '=', 6],['so', '=', 1]],
    [['shop_id', '=', 1],['product_id', '=', 6],['so', '=', 2]],
    [['shop_id', '=', 1],['product_id', '=', 6],['so', '=', 1],['state', '=', u'draft']],
    [['shop_id', '=', 1],['product_id', '=', 6],['so', '=', 2],['state', '=', u'draft']],
]

How do i achieve such data arrangement.Is there any short method available in python,

you would be better off creating a dictionary for this type of data — avasal
– avasal, Commented Feb 14, 2013 at 6:36

Yevgen Yampolskiy · Accepted Answer · 2013-02-14 07:25:21Z

4

You should use sorted:

sorted(in_put, key=lambda x: (
                    x[0][2],
                    {16:1,8:2,4:3,6:4}[x[1][2]] if len(x)>1 else None,
                    x[3][2] if len(x)>3 else None,
                    x[2][2] if len(x)>2 else None
                    ))

If product_id needs to be sorted as 16/8/6/4 (and not in the order in your example), then you can use

sorted(in_put, key=lambda x: (
                    x[0][2],
                    1.0/x[1][2] if len(x)>1 else None,
                    x[3][2] if len(x)>3 else None,
                    x[2][2] if len(x)>2 else None
                    ))

answered Feb 14, 2013 at 7:25

Yevgen Yampolskiy

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1 Comment

Hui Zheng Over a year ago

this is the right way, but why use 1.0/x[1][2] instead of -x[1][2]? The former is slower and unsafe(x[1][2] may be 0)

nneonneo · Accepted Answer · 2013-02-14 06:37:27Z

1

In general, I'd use sorted to get a copy of the list sorted according to some criteria.

In your particular case, it's not immediately applicable. Instead, we can do something like this:

output = [in_put[0]] + in_put[1::4] + in_put[2::4] + in_put[3::4] + in_put[4::4]

to rearrange the list as you wanted it. (Shorter yet, you can use zip).

answered Feb 14, 2013 at 6:37

nneonneo

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