keep attrs when reducing xray objects

[jhamman]

Reduction operations currently drop all Variable and Dataset attrs when a reduction operation is performed. I'm proposing adding a keyword to these methods to allow for copying of the original Variable or Dataset attrs.

The default value of the keep_attrs keyword would be False.

For example:

new = ds.mean(keep_attrs=True)

returns new with all the Variable and Dataset attrs as ds contained.

Some previous discussion in #131 and #137.

[shoyer]

This seems fine by me.

@akleeman Your thoughts?

[akleeman]

Yeah I agree, seems like a great option to have.

[ebrevdo]

Why not options like 'first', 'common', etc?
On May 20, 2014 11:52 PM, "akleeman" notifications@github.com wrote:

Yeah I agree, seems like a great option to have.

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[shoyer]

@ebrevdo This is for reduce operations like "mean" which are unary operators. But it does seem like a good idea to consider if/how this could be extended to binary operations (e.g., "merge" or "add"). To make this an option for mathematical operations like "add" we would need to add an add method for instead of just relying on overloading the + operator.