Fixed cfproto_cat_adult_ohe example

[RobertSamoilescu]

Replaced OHE sparse with OHE dense and fixed display function.
Addresses #749

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Codecov Report

Merging #750 (b252075) into master (e95e66b) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #750   +/-   ##
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  Coverage   80.96%   80.96%           
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  Files         105      105           
  Lines       11876    11876           
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  Hits         9615     9615           
  Misses       2261     2261           

[jklaise]

Testing this locally, this is not triggered with numpy version 1.20.3 but it is with version 1.22.4. Since the error originates from a call to np.percentile it appears that earlier numpy versions may have been able to handle np.matrix (which is the result of conversion from sparse to dense matrix in the original notebook) but no longer so.

[jklaise]

Thanks Robert, have tested this locally as well.