Support for schemas smaller than the dataframe

[diegoquintanav]

This is not the same as the existing support for columns.

In general terms

• having some schema that contains, say, 13 validations, one per column
• dataset that has 30 columns, of which the ones in the schema are a subset of

running validate() without passing the specific columns will fail, with something like

Invalid number of columns. The schema specifies 13, but the data frame has 30

I believe this should try to validate the subset, that is, validating the 13 columns that are in the schema.

[multimeric]

I think it's reasonable that PandasSchema throws an error here by default, but I agree there should be a flag to disable this. I'll look in to adding this once I get time (or you can, if you'd like)

In the meantime you can pass in a list of columns to validate, as you say.

[abhilasharevur]

Any update? I see the this is still in requests. Any plans of adding this to master?