CODEWITHSUNDEEP
pythonlistdictionarylinked-listnested
Guguma
Guguma

Reputation: 93

Convert Dash Seperated String Data to Nested Dictionary/List in Python

I have list of strings where each element in the list is in the specified format a-b-c where each a,b,c are integers, e.g, contains about 8000 elements lengths of n-m-k vary.

myList = ['1-1-1', '1-1-2', '1-2-1', '1-2-2', '1-3-1', ...., n-m-k]

I am trying to find a simple and efficient way to convert this into

myDict = {
'1': {
    '1-1': ['1-1-1','1-1-2','1-1-3','1-1-4'],
    '1-2': ['1-2-1','1-2-2'],
    '1-3': ['1-3-1']
},
....,
'n': {.....,'n-m':[....,'n-m-k']}
}

As I need to run operations based on these elements, like an in-place linked-list.

What is the easiest way to achieve this?

Thanks in Advance,

Upvotes: 2

Views: 321

Answers (3)

Ajax1234
Ajax1234

Reputation: 71461

You can use a list comprehension:

myList = ['1-1-1', '1-1-2', '1-2-1', '1-2-2', '1-3-1']
_split = list(map(lambda x:x.split('-'), myList))
s, s2 = {a for a, *_ in _split}, {f'{a}-{b}' for a, b, _ in _split}
new_data = {i:{c:[h for h in myList if h.startswith(c)] for c in s2 if c[0] == i} for i in s}

Output:

{'1': {'1-2': ['1-2-1', '1-2-2'], '1-1': ['1-1-1', '1-1-2'], '1-3': ['1-3-1']}

Upvotes: 1

pault
pault

Reputation: 43524

IIUC, your desired output is actually something like:

myDict = {
    '1': {
        '1-1': ['1-1-1','1-1-2','1-1-3','1-1-4'],
        '1-2': ['1-2-1','1-2-2'],
        '1-3': ['1-3-1']
    },
    ....,
    'n': {.....,'n-m':[....,'n-m-k']}
}`

Here's one way using itertools.groupby:

from itertools import groupby
myList = [
    '1-1-1','1-1-2','1-2-1','1-2-2','1-3-1', '2-1-1', '2-2-2', '2-2-3', '4-5-6'
]

# a helper function
def mySplit(s, max_split):
    return {
        v: list(g) 
        for v, g in groupby(
            s, 
            lambda x: "-".join(x.split("-", max_split)[:max_split])
        )
    }

myDict = {v: mySplit(g, 2) for v, g in groupby(myList, lambda x: x.split("-", 1)[0])}

print(myDict)
#{'1': {'1-1': ['1-1-1', '1-1-2'], '1-2': ['1-2-1', '1-2-2'], '1-3': ['1-3-1']},
# '2': {'2-1': ['2-1-1'], '2-2': ['2-2-2', '2-2-3']},
# '4': {'4-5': ['4-5-6']}}

With some work, this can be generalized to work for an arbitrary number of dashes.

Upvotes: 1

James
James

Reputation: 36691

If can accept tuples of integers, you can use:

x = ['1-1-1','1-1-2', '1-2-1', '1-2-2', '1-3-1']
y3 = [tuple(map(int,a.split('-'))) for a in x]
y2 = set(a[:2] for a in y3)
y1 = set(a[0] for a in y2)

d = {}
for k1 in y1:
    d1 = {}
    d[k1] = d1
    for k2 in (z for z in y2 if z[0]==k1):
        a2 = []
        d1[k2] = a2
        for a in (z for z in y3 if z[0]==k1 and z[1]==k2[1]):
            a2.append(a)

But if you really need strings, you can simply join the keys via:

x = ['1-1-1','1-1-2', '1-2-1', '1-2-2', '1-3-1']
y3 = [tuple(a.split('-')) for a in x]
y2 = set(a[:2] for a in y3)
y1 = set(a[0] for a in y2)


d = {}
for k1 in y1:
    d1 = {}
    d[k1] = d1
    for k2 in (z for z in y2 if z[0]==k1):
        a2 = []
        d1['-'.join(k2)] = a2
        for a in (z for z in y3 if z[0]==k1 and z[1]==k2[1]):
            a2.append('-'.join(a))

d
# returns:
{'1': {'1-1': ['1-1-1', '1-1-2'], '1-2': ['1-2-1', '1-2-2'], '1-3': ['1-3-1']}}

Upvotes: 1

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