loss weight is not set to a default value

[lucaventurini]

Describe the bug

As in title. The bug appears when we set positive_class_weight

To Reproduce

The following:

    name: MyClass
    type: binary
    loss:
        positive_class_weight: 231.58892815076564

throws an exception in:
File "/usr/local/lib/python3.6/dist-packages/ludwig/features/base_feature.py", line 317, in concat_dependencies_and_build_output loss_weight = float(self.loss['weight'])

This instead works:

    name: MyClass
    type: binary
    loss:
        positive_class_weight: 231.58892815076564
        weight: 1

Expected behavior
loss.weight should be set to a default value?

Environment (please complete the following information):

• OS: Ubuntu
• Python version 3.6
• Ludwig version 0.2.2

[w4nderlust]

Should be fixed, please confirm by installing from master:

pip uninstall ludwig
pip install git+http://github.com/uber/ludwig.git