Assert in Java
- Avoid using
assertin Java production code as assertion is not turned on by default. Throw exception instead (since assert is just a syntax sugar of throwing exceptions).
The most important thing to remember about assertions is that they can be disabled, so never assume they'll be executed.
Therefore keep the followings things in mind when using assertions:
MutableList in Kotlin
MutableList vs ArrayList¶
MutableList is ArrayList in Kotlin currently.
Create an Empty MutableList¶
Below is the most idiomatical way to create an empty mutable list in Kotlin.
Python Virtual Environment
Things on this page are fragmentary and immature notes/thoughts of the author. Please read with your own judgement!
Dataframe for JVM
Things on this page are fragmentary and immature notes/thoughts of the author. Please read with your own judgement!
Spark DataFrame
Spark DataFrame is a great implementation of distributed DataFrame, if you don't mind having dependency on Spark. It can be used in a non-distributed way of course. Spark DataFrame …
Row-based Mapping and Filtering on DataFrames in Spark
Comments¶
Spark DataFrame is an alias to Dataset[Row].
Even though a Spark DataFrame is stored as Rows in a Dataset,
built-in operations/functions (in org.apache.spark.sql.functions) for Spark DataFrame are Column-based.
Sometimes,
there might be transformations on a DataFrame that is hard to express as Column expressions
but rather evey convenient to express as Row expressions.
The traditional way to resolve this issue is to wrap the row-based function into a UDF.
It is worthing knowing that Spark DataFrame supports map/flatMap APIs
which works on Rows.
They are still experimental as Spark 2.4.3.
It is suggested that you stick to Column-based operations/functions until the Row-based methods mature.