Latest version of altair seems to have broken LayeredChart()

I tried this code both on desktop Jupyter notebook and in Azure notebook. It used to work in both.

With appropriately defined pandas dataframe named ‘data’ c=LayeredChart(data) c+=Chart().mark_line(color='green').encode(x="x",y="y") c+=Chart().mark_line(color='blue').encode(x='x',y='y2') c

This produces the error:

AttributeErrorTraceback (most recent call last)
/home/nbuser/anaconda2_410/lib/python2.7/site-packages/IPython/core/formatters.pyc in __call__(self, obj)
    913             method = get_real_method(obj, self.print_method)
    914             if method is not None:
--> 915                 method()
    916                 return True
    917 

/home/nbuser/anaconda2_410/lib/python2.7/site-packages/altair/v1/api.pyc in _ipython_display_(self)
    443         from IPython.display import display
    444         from vega import VegaLite
--> 445         display(VegaLite(self.to_dict(validate_columns=True)))
    446 
    447     def display(self):

/home/nbuser/anaconda2_410/lib/python2.7/site-packages/altair/v1/api.pyc in to_dict(self, data, validate_columns)
    287             The JSON specification of the chart object.
    288         """
--> 289         dct = super(TopLevelMixin, self.clone()).to_dict(data=data, validate_columns=validate_columns)
    290         dct['$schema'] = schema.vegalite_schema_url
    291         return dct

/home/nbuser/anaconda2_410/lib/python2.7/site-packages/altair/v1/schema/_interface/jstraitlets.pyc in to_dict(self, **kwargs)
    151     def to_dict(self, **kwargs):
    152         """Output a (nested) dict encoding the contents of this instance"""
--> 153         self._finalize(**kwargs)
    154         Visitor = self._converter_registry.get('to_dict', ToDict)
    155         return Visitor().visit(self, **kwargs)

/home/nbuser/anaconda2_410/lib/python2.7/site-packages/altair/v1/api.pyc in _finalize(self, **kwargs)
    503         # and the Chart allows it.
    504         if validate_columns and self.validate_columns:
--> 505             self._validate_columns()
    506 
    507     def _finalize_data(self):

/home/nbuser/anaconda2_410/lib/python2.7/site-packages/altair/v1/api.pyc in _validate_columns(self)
    569             # Find columns with visual encodings
    570             encoded_columns = set()
--> 571             encoding = self.encoding
    572             if encoding is not jst.undefined:
    573                 for channel_name in encoding.channel_names:

AttributeError: 'LayeredChart' object has no attribute 'encoding'

Out[9]:
<traitlets.traitlets.LayeredChart at 0x7f6b1c605750>

[iliatimofeev]

alt.layer(points, lines, data = df) will work. Altair 2.0.1 has totally new syntax for layered charts as vega-lite 2 do. Please check documentation on compound charts.

[jakevdp]

The add_selection method was added in Altair version 2.1. If you update Altair, it should work.