Need to filter list of dictionaries-CodePudding

I have one large list of dictionaries pulled from a database. I'm wondering if there is a way to search the first list of dicts to only show the first 3 digits (list would be unique to avoid duplicate entries) in one dropdown menu and, based on the selection, show the appropriate options?

Essentially the first dropdown would show selectable options "220, 221, 222, 223, 224", let's say we selected "220", then the second dropdown would show '220_2_INTL_PRSTR_ET_619076', '220_4_KAL_T2E_DOLE_344657'. I'm not worried about the code needed to create the dropdowns, just the filtering of the list of dicts to achieve the results.

list_of_dict = [ 
{'label': '220_2_INTL_PRSTR_ET_619076', 'value': '220_2_INTL_PRSTR_ET_619076'}, 
{'label': '220_4_KAL_T2E_DOLE_344657', 'value': '220_4_KAL_T2E_DOLE_344657'}, 
{'label': '221_1_PB_520_REF_174049', 'value': '221_1_PB_520_REF_174049'},
{'label': '222_5_KAL_T2E_YT_344991', 'value': '222_5_KAL_T2E_YT_344991'}, 
{'label': '223_2_PB_520_REF_174050', 'value': '223_2_PB_520_REF_174050'}, , 
{'label': '224_3_PB_520_REF_174051', 'value': '224_3_PB_520_REF_174051'}]

CodePudding user response：

It's fairly straightforward to turn your list into a dictionary that has exactly what you need:

list_of_dict = [
    {'label': '220_2_INTL_PRSTR_ET_619076', 'value': '220_2_INTL_PRSTR_ET_619076'},
    {'label': '220_4_KAL_T2E_DOLE_344657', 'value': '220_4_KAL_T2E_DOLE_344657'},
    {'label': '221_1_PB_520_REF_174049', 'value': '221_1_PB_520_REF_174049'},
    {'label': '222_5_KAL_T2E_YT_344991', 'value': '222_5_KAL_T2E_YT_344991'},
    {'label': '223_2_PB_520_REF_174050', 'value': '223_2_PB_520_REF_174050'},
    {'label': '224_3_PB_520_REF_174051', 'value': '224_3_PB_520_REF_174051'}
]

# it's a "one-liner", a dict comprehension split over a few lines for readability:
result = {
    p: [d for d in list_of_dict if d['label'].startswith(p)]
    for p in set(d['label'][:3] for d in list_of_dict)
}

print(result['220'])  # the contents for this prefix
print(result.keys())  # the keys for your first dropdown

Output:

[{'label': '220_2_INTL_PRSTR_ET_619076', 'value': '220_2_INTL_PRSTR_ET_619076'}, {'label': '220_4_KAL_T2E_DOLE_344657', 'value': '220_4_KAL_T2E_DOLE_344657'}]
['222', '220', '224', '223', '221']

Note that the keys are out of order, but sorting is straightforward.

Instead of d['label'][:3] you could consider d['label'].split('_')[0], if the prefixes aren't all 3 characters long, but instead are "everything before the first underscore".

CodePudding user response：

Given a prefix, the filtering code comes down to an if-statement and a str.startwith() test:

prefix = '220'
for d in list_of_dict:
    if d['label'].startswith(prefix):
        print(d)

For purposes of a dropdown menu, it may be preferable to group the data in advance using defaultdict() and extracting the prefix with slicing:

from collections import defaultdict

grouped = defaultdict(list)
for d in list_of_dict:
    prefix = d['label'][:3]
    grouped[prefix].append( d['value'])

Now you can lookup results directly:

>>> grouped['220']
['220_2_INTL_PRSTR_ET_619076', '220_4_KAL_T2E_DOLE_344657']

This strategy is also faster than filtering the entire list for every lookup.

CodePudding user response：

As first step, you can use set() to obtain the first tree characters from labels without duplicates.

Then you can create a function to filter the list using str.startswith:

def get_options(l):
    return {d["label"][:3] for d in l}


def filter_list(l, s):
    return [d for d in l if d["label"].startswith(s)]


print(get_options(list_of_dict))
print(filter_list(list_of_dict, "220"))

Prints:

{"222", "221", "224", "220", "223"}
[
    {
        "label": "220_2_INTL_PRSTR_ET_619076",
        "value": "220_2_INTL_PRSTR_ET_619076",
    },
    {
        "label": "220_4_KAL_T2E_DOLE_344657",
        "value": "220_4_KAL_T2E_DOLE_344657",
    },
]