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API Introduction🔗

Fliq provides rich functionality to perform processing on datasets (aka iterables). This reference section provides concepts and a detailed description of the API.

Note

API docs contain type aliases to improve readability:

  • Predicate. Predicate = Callable[[T], bool]
  • Selector. Selector = Callable[[T], U]
  • NumericSelector = Selector[T, Union[int, float]]
  • IndexSelector = Selector[T, int]

Query🔗

Query is the main object in Fliq. It is an abstracted lazy iterable, which can be used to perform processing on datasets.

Query should be perceived as a generator-like collection.

  • It provides built-in iterable functionality (such as for, in etc.).
  • It can be exhausted (used only once).
from fliq import q
q([1, 2, 3, 4]).where(lambda x: x % 2 == 0).select(lambda x: x * 2).to_list() 
# [4, 8]

The main functionality of Query can be divided into two categories: Mappers methods and Materializer methods.

Mapper Methods🔗

Mapper methods (aka mappers) are used to transform the data in the Query. They are lazy, and follow fluent syntax. They can be chained together to create complex transformations that are lazy, so they are only executed on demand. Mappers are implemented using the standard python library, so they are highly efficient and performant.

from fliq import q
q([0, 1, 2]).where(lambda x: x % 2 == 0).select(lambda x: x + 1) 
# Query object similar to [1, 3]

For the full list of mappers, please refer to the Mapper Methods section.

Materializer Methods🔗

Materializer methods (aka materializers) are used to perform some action, and return a concrete result. To do that, they materialize the data in the Query (i.e., execute delayed computation, chained thus far).

A Materializer that aggregates the iterable to return a single value is called a Reducer. Most materializers are in-fact reducers.

from fliq import q
q([0, 1, 2]).max() 
# 2

There are other materializers, which do not aggregate the iterable to a single value. For example, to_list returns a list of all the items in the iterable.

from fliq import q
q([0, 1, 2]).where(lambda x: x % 2 == 0).to_list() 
# [0, 2]

For the full list of mappers, please refer to the Materializer Methods section.

Special Functionality🔗

You can also find special functionality in the Query API, such as snapshots (snap()). See the relevant pages under the Reference section for more information.