Support strip, lstrip, and rstrip in strings_udf

[brandon-b-miller]

This PR adds support for the following three functions in strings_udf:

• str.strip(other)
• str.lstrip(other)
• str.rstrip(other)

Part of #9639

[vyasr]

Some minor suggestions for improvement. Feel free to merge once you've addressed, I don't need to look again unless something new comes up (in which case feel free to re-request).

[vyasr]

This name is somewhat misleading. There are other string binary functions that we already have implemented, including operators and things like find and contains. Is this list meant to contain binary string functions that also return a string, or is it even more specific than that?

[brandon-b-miller]

Renaming this to string_return_attrs

[vyasr]

Are tests failing because there's somewhere extra that needs to have the new method attributes added?

E                   numba.core.errors.TypingError: Failed in cuda mode pipeline (step: nopython frontend)
E                   #x1B[1m#x1B[1mUnknown attribute 'strip' of type Masked(Poison<#x1B[91m
E                   strings_udf library required for usage of string dtypes inside user defined functions.
E                   #x1B[0m>)
E                   #x1B[1m
E                   File "tests/test_udf_masked_ops.py", line 882:#x1B[0m
E                   #x1B[1m    def func(row):
E                   #x1B[1m        return row["str_col"].strip(strip_char)
E                   #x1B[0m        #x1B[1m^#x1B[0m#x1B[0m
E                   #x1B[0m

[brandon-b-miller]

Are tests failing because there's somewhere extra that needs to have the new method attributes added?

I think this is just because those tests need to be marked @string_udf_test.

[brandon-b-miller]

@davidwendt I'm getting one failing test locally for the following string using:

>>> import cudf
>>> sr = cudf.Series(['.123a'])
>>> def f(st):
...     return st.lstrip('a')
... 
>>> sr.apply(f)
0    .123
dtype: object

It looks like this rstrip'ed the string rather than lstrip'ed it. Interestingly the reverse is also a fail case:

>>> import cudf
>>> sr = cudf.Series(['.123a'])
>>> def f(st):
...     return st.rstrip('.')
... 
>>> sr.apply(f)
0    123a
dtype: object
>>> 

Here it looks like this was lstrip'ed instead of rstrip'ed.

[davidwendt]

Here it looks like this was lstrip'ed instead of rstrip'ed.

I'm not seeing this error in my unit tests

  auto input = cudf::string_view(".123a",5);
  auto achr = cudf::string_view("a",1);
  auto dot = cudf::string_view(".",1);

  d_str = cudf::strings::udf::strip( input, achr, cudf::strings::side_type::LEFT );
  printf("lstrip(.123a,a)=[%s]\n", d_str.data());
  d_str = cudf::strings::udf::strip( input, dot, cudf::strings::side_type::LEFT );
  printf("lstrip(.123a,.)=[%s]\n", d_str.data());
  d_str = cudf::strings::udf::strip( input, achr, cudf::strings::side_type::RIGHT );
  printf("rstrip(.123a,a)=[%s]\n", d_str.data());
  d_str = cudf::strings::udf::strip( input, dot, cudf::strings::side_type::RIGHT );
  printf("rstrip(.123a,.)=[%s]\n", d_str.data());

lstrip(.123a,a)=[.123a]
lstrip(.123a,.)=[123a]
rstrip(.123a,a)=[.123]
rstrip(.123a,.)=[.123a]

Could the problem be that all of these are calling just strip() ?

cudf/python/strings_udf/strings_udf/lowering.py

Lines 59 to 67 in 302fe60

	_string_view_strip = cuda.declare_device(
	"strip", types.int32(_UDF_STRING_PTR, _STR_VIEW_PTR, _STR_VIEW_PTR)
	)
	_string_view_lstrip = cuda.declare_device(
	"strip", types.int32(_UDF_STRING_PTR, _STR_VIEW_PTR, _STR_VIEW_PTR)
	)
	_string_view_rstrip = cuda.declare_device(
	"strip", types.int32(_UDF_STRING_PTR, _STR_VIEW_PTR, _STR_VIEW_PTR)
	)

[brandon-b-miller]

@davidwendt you're completely right, with 02167d3 the tests pass.

[codecov]

Codecov Report

Base: 88.05% // Head: 88.08% // Increases project coverage by +0.02% 🎉

Coverage data is based on head (c281108) compared to base (35077f5).
Patch coverage: 93.18% of modified lines in pull request are covered.

❗ Current head c281108 differs from pull request most recent head 3539ed7. Consider uploading reports for the commit 3539ed7 to get more accurate results

Additional details and impacted files

@@               Coverage Diff                @@
##           branch-22.12   #12091      +/-   ##
================================================
+ Coverage         88.05%   88.08%   +0.02%     
================================================
  Files               135      135              
  Lines             22057    22092      +35     
================================================
+ Hits              19423    19459      +36     
+ Misses             2634     2633       -1     

Impacted Files	Coverage Δ
python/strings_udf/strings_udf/lowering.py	84.97% <86.36%> (+<0.01%)	⬆️
python/cudf/cudf/core/udf/__init__.py	100.00% <100.00%> (ø)
python/cudf/cudf/core/udf/strings_lowering.py	100.00% <100.00%> (ø)
python/cudf/cudf/core/udf/strings_typing.py	97.26% <100.00%> (+0.07%)	⬆️
python/cudf/cudf/utils/ioutils.py	80.18% <100.00%> (+0.38%)	⬆️
python/strings_udf/strings_udf/_typing.py	97.22% <100.00%> (+0.07%)	⬆️
python/strings_udf/strings_udf/__init__.py	84.31% <0.00%> (+7.84%)	⬆️

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[brandon-b-miller]

@gpucibot merge