iode.Tables.subset

Tables.subset(pattern: str, copy: bool) → Self[source]

Create a subset of the database filtered by a name pattern.

This method creates filtered views or independent copies of the database. It supports two modes of operation controlled by the copy parameter:

  • View mode (copy=False): Creates a database object that acts as a view of the global workspace. Any changes made to the view are reflected in the global workspace and vice versa.

  • Copy mode (copy=True): Creates a new detached database containing copies of the matched objects. Changes made to the copy do not affect the global workspace.

The pattern argument can represent a single object name (e.g. “ACAF”) or a list of object names (“ACAF;ACAG;AOUC”) or a pattern (e.g. “A*”) or a list of sub-patterns (e.g. “A*;*_”).

If the pattern argument represents a list of object names or of sub-patterns, each name or sub-pattern is separated by a separator character which is either a whitespace ` , or a comma `,, or a semi-colon ;, or a tabulation t, or a newline n.

A (sub-)pattern is a list of characters representing a group of object names. It includes some special characters which have a special meaning:

  • * : any character sequence, even empty

  • ? : any character (one and only one)

  • @ : any alphanumerical char [A-Za-z0-9]

  • & : any non alphanumerical char

  • | : any alphanumeric character or none at the beginning and end of a string

  • ! : any non-alphanumeric character or none at the beginning and end of a string

  • `` : escape the next character

Note that the pattern argument can contain references to IODE lists which are prefixed with the symbol $.

Parameters:
patternstr

Pattern to filter object names. Syntax is the same as used in __getitem__ method. It can contain the following special characters:

  • * : any character sequence, even empty

  • ? : any character (one and only one)

  • @ : any alphanumerical char [A-Za-z0-9]

  • & : any non alphanumerical char

  • | : any alphanumeric character or none at the beginning and end of a string

  • ! : any non-alphanumeric character or none at the beginning and end of a string

  • `` : escape the next character

Examples:

  • “A*”: All objects whose name starts with ‘A’

  • “*_”: All objects whose name ends with ‘_’

  • “A*;*_”: All objects starting with ‘A’ or ending with ‘_’

  • “*”: All objects (match all pattern)

  • “”: No objects (empty pattern)

copybool

If True, creates a new detached database with independent copies of the matched objects. Changes to this database will not affect the global workspace.

If False, creates a view of the global workspace filtered using a pattern. Changes to this view are reflected in the global workspace.

Returns:
Database

A new database instance of the same type, either as a view or a detached copy depending on the copy parameter.

See also

IodeDatabase.copy

Create a copied subset with pattern filtering

IodeDatabase.new_detached

Create a new empty detached database

IodeDatabase.__getitem__

Create a view subset using bracket notation

Examples

>>> from iode import SAMPLE_DATA_DIR
>>> from iode import comments
>>> comments.load(f"{SAMPLE_DATA_DIR}/fun.cmt")
Loading .../fun.cmt
317 objects loaded

View mode (copy=False) - linked to global workspace

>>> # Create a view of objects starting with 'A'
>>> cmt_subset = comments.subset("A*", copy=False)
>>> cmt_subset.is_detached
False
>>> # Changes in the view affect the global workspace
>>> cmt_subset["ACAF"] = "Modified in view"
>>> comments["ACAF"]
'Modified in view'
>>> # Modifications in global workspace are visible in view
>>> comments["ACAF"] = "Modified globally"
>>> cmt_subset["ACAF"]
'Modified globally'

Single object view >>> cmt_single_obj_subset = comments.subset(“ACAF”, copy=False) >>> cmt_single_obj_subset # doctest: +ELLIPSIS, +NORMALIZE_WHITESPACE Workspace: Comments nb comments: 1 filename: …fun.cmt <BLANKLINE> name comments ACAF Modified globally <BLANKLINE>

Copy mode (copy=True) - independent from global workspace

>>> # Create a copy of objects starting with 'B'
>>> cmt_copy_subset = comments.subset("B*", copy=True)
>>> cmt_copy_subset.is_detached
True
>>> cmt_copy_subset.names
['BENEF', 'BENEF_', 'BQY', 'BVY']
>>> # Changes in copy do not affect global workspace
>>> cmt_copy_subset["BENEF"] = "Modified only in copy"
>>> comments["BENEF"]
'Ondernemingen: niet-uitgekeerde winsten.'

Empty database (new_detached)

>>> # Create an empty detached database
>>> cmt_empty_subset = comments.subset("", copy=True)
>>> cmt_empty_subset.is_detached
True
>>> cmt_empty_subset.names
[]
>>> len(cmt_empty_subset)
0