Merge/Join pandas DataFrames
Reference¶
https://pandas.pydata.org/pandas-docs/stable/merging.html
http://stackoverflow.com/questions/22676081/pandas-the-difference-between-join-and-merge
Comment¶
You are able to specify (via
left_onandright_on) which columns to join in each data frame.Columns that appear in both data frames but not used in joining are distinguished using suffixes.
Pivot Table in pandas DataFrame
DataFrame.pivot vs pandas.pivot_table¶
- Both
DataFrame.pivotandpandas.pivot_tablecan generate pivot tables.pandas.pivot_tableaggregate values whileDataFrame.pivotnot.
Loops in Java
Things on this page are fragmentary and immature notes/thoughts of the author. Please read with your own judgement!
-
The condition(s) in a regular
fororwhileloop is recomputed before each iteration. Not only the change of loop variables but also other variables involved in the loop condition …
Arrays in Java
Comments¶
- An array in Java is not an
Iterable(due to design reasons). There is no super class of array andIterableeither in Java. If you want a method to support both array andIterableas the parameter, you need to overload it (for both array andIterable.) It is the same situation in Kotlin as Kotlin is mostly Java.