Strings Extract#

group Extracting

Functions

std::unique_ptr<table> extract(strings_column_view const &input, regex_program const &prog, rmm::cuda_stream_view stream = cudf::get_default_stream(), rmm::device_async_resource_ref mr = cudf::get_current_device_resource_ref())#

Returns a table of strings columns where each column corresponds to the matching group specified in the given regex_program object.

All the strings for the first group will go in the first output column; the second group go in the second column and so on. Null entries are added to the columns in row i if the string at row i does not match.

Any null string entries return corresponding null output column entries.

Example:
s = ["a1", "b2", "c3"]
p = regex_program::create("([ab])(\\d)")
r = extract(s, p)
r is now [ ["a", "b", null],
           ["1", "2", null] ]

See the Regex Features page for details on patterns supported by this API.

Parameters:

  • input – Strings instance for this operation

  • prog – Regex program instance

  • stream – CUDA stream used for device memory operations and kernel launches

  • mr – Device memory resource used to allocate the returned table’s device memory

Returns:

Columns of strings extracted from the input column

std::unique_ptr<column> extract_all_record(strings_column_view const &input, regex_program const &prog, rmm::cuda_stream_view stream = cudf::get_default_stream(), rmm::device_async_resource_ref mr = cudf::get_current_device_resource_ref())#

Returns a lists column of strings where each string column row corresponds to the matching group specified in the given regex_program object.

All the matching groups for the first row will go in the first row output column; the second row results will go into the second row output column and so on.

A null output row will result if the corresponding input string row does not match or that input row is null.

Example:
s = ["a1 b4", "b2", "c3 a5", "b", null]
p = regex_program::create("([ab])(\\d)")
r = extract_all_record(s, p)
r is now [ ["a", "1", "b", "4"],
           ["b", "2"],
           ["a", "5"],
           null,
           null ]

See the Regex Features page for details on patterns supported by this API.

Parameters:

  • input – Strings instance for this operation

  • prog – Regex program instance

  • stream – CUDA stream used for device memory operations and kernel launches

  • mr – Device memory resource used to allocate any returned device memory

Returns:

Lists column containing strings extracted from the input column

std::unique_ptr<column> extract_single(strings_column_view const &input, regex_program const &prog, size_type group, rmm::cuda_stream_view stream = cudf::get_default_stream(), rmm::device_async_resource_ref mr = cudf::get_current_device_resource_ref())#

Returns a strings column where each column corresponds to the specified group in the given regex_program object.

Any null string entries return corresponding null output for that row.

Example:
s = ["a1", "b2", "c3"]
p = regex_program::create("([ab])(\\d)")
r = extract(s, p, 1)
r is now [ "1", "2", "3" ]

See the Regex Features page for details on patterns supported by this API.

Parameters:

  • input – Strings instance for this operation

  • prog – Regex program instance

  • group – Index of the group number to extract

  • stream – CUDA stream used for device memory operations and kernel launches

  • mr – Device memory resource used to allocate the returned table’s device memory

Returns:

Columns of strings extracted from the input column