Version 0.8.0

We added new functionalities, improved the documentation and fixed some bugs in the past week. Also, koalas.sql has an improvement (#448). Now Koalas DataFrame and some regular Python types can be used directly in SQL, for instance, as below:

>>> mydf = ks.range(10)
>>> x = range(4)
>>> ks.sql("SELECT * from {mydf} WHERE id IN {x}")
   id
0   0
1   1
2   2
3   3

We also added the following features:

koalas

• read_spark_io (#447)
• read_table (#449)
• read_delta (#456)

koalas.DataFrame:

• append (#388)
• from_records (#436)
• to_parquet (#443)
• to_spark_io (#447)
• to_table (#449)
• cache (#397)
• to_delta (#456)
• drop_duplicates (#458)

koalas.Series:

• append (#388)
• str (#429)
• plot (#294)
• hist (#294)

Along with the following improvements:

• mean, sum, skew, kurtosis, min, max, std and var at DataFrame and Series supports numeric_only argument (#422)