Preference Libraries

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Preference Libraries#

See Preference Libraries for a reference.

We provide support for standard preference libraries.

PaBuLib#

Full support is provided for the participatory budgeting data hosted on the pabulib website. You can use the function parse_pabulib() to parse a file that conforms to the pabulib format. This function yields the instance and profile based on the appropriate profile class determined by the ballot format in the data.

from pabutools.election import parse_pabulib

instance, profile = parse_pabulib("path_to_the_file")

Pabulib files contain an extensive range of metadata. This metadata is stored in the meta members of the instance and profile classes.

from pabutools.election import parse_pabulib

instance, profile = parse_pabulib("path_to_the_file")
instance.meta   # The meta dict is populated with all the metadata described in the file
instance.project_meta    # The project_meta dict is populated with the metadata related to the projects
for ballot in profile:
    ballot.meta    # The meta dict populated with the metadata corresponding to the ballot

Several metadata is housed as members of the corresponding classes. For example, all known constraints that the voters were subjected to when submitting their ballots. This includes the minimum length of a ballot or the number of points that must be allocated for instance.

### For ApprovalProfile, CardinalProfile, CumulativeProfile, and OrdinalProfile
profile.legal_min_length   # Imposed minimum length of the ballots in the profile
profile.legal_max_length   # Imposed maximum length of the ballots in the profile

### For ApprovalProfile only
profile.legal_min_cost   # Imposed minimum total cost of the ballots in the profile
profile.legal_max_cost   # Imposed maximum total cost of the ballots in the profile

### For CardinalProfile and CumulativeProfile
profile.legal_min_score   # Imposed minimum score assigned to a project for the ballots in the profile
profile.legal_max_score   # Imposed maximum score assigned to a project for the ballots in the profile

### For CumulativeProfile only
profile.legal_min_total_score   # Imposed minimum total scores for the ballots in the profile
profile.legal_max_total_score   # Imposed maximum total scores for the ballots in the profile

It is also possible to write instances and profiles into Pabulib files:

from pabutools.election import write_pabulib

write_pabulib(instance, profile, "path/to/the/file.pb")

If you need the string corresponding to the file content, you can use the following:

from pabutools.election.pabulib import election_as_pabulib_string

str_representation = election_as_pabulib_string(instance, profile)

PrefLib#

In addition to pabulib , our package also supports the preflib format, providing functions to convert a participatory budgeting election into a PrefLib instance.

from pabutools.election import Instance, ApprovalProfile, CardinalProfile, OrdinalProfile
from pabutools.election import approval_to_preflib, cardinal_to_preflib, ordinal_to_preflib

instance = Instance()

# Approval profiles are mapped to categorical instances for PrefLib
app_profile = ApprovalProfile()
preflib_instance = approval_to_preflib(instance, app_profile)

# Cardinal profiles are mapped to ordinal instances for PrefLib
card_profile = CardinalProfile()
preflib_instance = cardinal_to_preflib(instance, card_profile)

# Ordinal profiles are mapped to ordinal instances for PrefLib
ord_profile = ApprovalProfile()
preflib_instance = ordinal_to_preflib(instance, ord_profile)
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