Adding a LoadColumnNameAttribute

[tannergooding]

This resolves #4195

[tannergooding]

CC. @eerhardt, @CESARDELATORRE, @luisquintanilla

[CESARDELATORRE]

Not sure I understand this. What if you have hundreds of columns to be loaded as a single vector. Do you need to specify all the column names? Can't you specify a column index range?

[tannergooding]

What would it mean to have a name and range? Why not just use the more efficient index based LoadColumn attribute at that point?

[CESARDELATORRE]

Sorry, that's what I mean, to use the LoadColumn attribute for those cases. I was thinking about the LoadColumn attribute. I didn't realize that here you are using LoadColumnName, not the same attribute, ok. ;)

[eerhardt]

        /// Source index range(s) of the column.

This comment is now a bit out-of-date.

Source index range(s) of the column.

Range can now be more than just index ranges. #Closed

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Refers to: src/Microsoft.ML.Experimental/DataLoadSave/Database/DatabaseLoader.cs:240 in 90316ec. [](commit_id = 90316ec, deletion_comment = False)

[eerhardt]

    /// Specifies the range of indices of input columns that should be mapped to an output column.

This comment is now a bit out-of-date.

the range of indices of input columns

Range can now be more than just indices. #Closed

---

Refers to: src/Microsoft.ML.Experimental/DataLoadSave/Database/DatabaseLoader.cs:253 in 90316ec. [](commit_id = 90316ec, deletion_comment = False)

[codecov]

Codecov Report

Merging #4308 into master will decrease coverage by 0.01%.
The diff coverage is 43.07%.

@@            Coverage Diff             @@
##           master    #4308      +/-   ##
==========================================
- Coverage   74.57%   74.56%   -0.02%     
==========================================
  Files         878      879       +1     
  Lines      154277   154524     +247     
  Branches    16874    16883       +9     
==========================================
+ Hits       115058   115220     +162     
- Misses      34472    34553      +81     
- Partials     4747     4751       +4

Flag	Coverage Δ
#Debug	74.56% <43.07%> (-0.02%)	⬇️
#production	70.14% <29.7%> (-0.03%)	⬇️
#test	89.54% <89.65%> (ø)	⬆️

Impacted Files	Coverage Δ
...l/DataLoadSave/Database/LoadColumnNameAttribute.cs	100% <100%> (ø)
...perimental/DataLoadSave/Database/DatabaseLoader.cs	52.39% <67.27%> (+3.8%)	⬆️
test/Microsoft.ML.Tests/DatabaseLoaderTests.cs	90.9% <89.65%> (-0.68%)	⬇️
...ntal/DataLoadSave/Database/DatabaseLoaderCursor.cs	22.62% <9.48%> (-2.19%)	⬇️
....ML.AutoML/PipelineSuggesters/PipelineSuggester.cs	79.83% <0%> (-3.37%)	⬇️
src/Microsoft.ML.Maml/MAML.cs	24.75% <0%> (-1.46%)	⬇️
src/Microsoft.ML.Transforms/Text/LdaTransform.cs	84.44% <0%> (-0.16%)	⬇️
...c/Microsoft.ML.Dnn/ImageClassificationTransform.cs	87.42% <0%> (-0.02%)	⬇️
test/Microsoft.ML.Functional.Tests/Evaluation.cs	100% <0%> (ø)	⬆️
... and 9 more

[eerhardt]

LGTM. Thanks!