to_csv does not support DataFrame indexes

[kbzowski]

Indexes in DataFrame are not saved when exporting to csv using to_csv.

const df = new DataFrame(input, { index: ['A', 'B', 'C'] } );
df.to_csv(filename);

[risenW]

Indexes in DataFrame are not saved when exporting to csv using to_csv.

const df = new DataFrame(input, { index: ['A', 'B', 'C'] } );
df.to_csv(filename);

Not currently supported.

[Emporea]

Is this related to #361? toJSON() also didnt't include the index.

It seems like most of the io files need an update so that Series and DataFrames include the index too.

[risenW]

Is this related to #361? toJSON() also didnt't include the index.

It seems like most of the io files need an update so that Series and DataFrames include the index too.

Yes, it's similar. If you want and can, you can raise a separate PR for this.