creating dynamic lists with configured values in python-CodePudding

Am trying to create dynamically generated lists depending on the configured value and needs a specific key for each list for example

configured value is 4 and list of numbers are [1,2,3,4,5,6,7,8,9] then this should be converted to

 key    list
-----------------
4      [1,2,3,4]
8      [5,6,7,8]
12     [9]

If configured value is 4 then always 1234 should be in first list and 5678 in second list If the values are [1,2,3,6,7,8,9] then the result should be

key    list
-----------------
4      [1,2,3]
8      [6,7,8]
12     [9]

Tried below code and am able to create list but not the key. Also feels coded many lines to create the list.

def dicttest(data):
    data.sort()
    result = pd.DataFrame({'ids': data})
    howmany = 4
    listcount = (result['ids'].max() // howmany)   1
    lists = []
    for x in range(listcount):
        lists.append(x * howmany)
    result['range'] = pd.cut(result.ids, lists, precision=0).astype(str)
    result = result.groupby('range').ids.apply(list).reset_index()

    return result

getting below result

range    ids
---------------
(0,4]    [1,2,3]
(4,8]    [6,7,8]
nan      [9]

It will be ok to get the result in dataframe OR dictionary with key and list of ids.

CodePudding user response：

There is an easier way to get key and perform your operation

You can simply calculate each number floor-divided by 4, and group by that. No need for pd.cut. (Though there is some complexity as show below to ensure value 4 is in row with key 4 and value 8 is in row with key 8, etc.)

def dicttest(data, howmany = 4):
    data.sort()
    result = pd.DataFrame({'sites': data})
    result['key'] = ((result['sites']-1) // howmany    1) * howmany 
    result = result.groupby('key').sites.apply(list)
    return result.to_dict()

The operation ((result['sites']-1) // 4 1) * 4 makes sure the value 4 in the list is placed in group with key 4. The operation does (4-1) // 4 1) * 4 => 4.
For the 1st row, the key becomes ((1-1)// 4 1) * 4 = 4`

Output:

>>> dicttest([1,2,3,4,5,6,7,8,9], howmany=4)
{4: [1, 2, 3, 4], 8: [5, 6, 7, 8], 12: [9]}