1/ Indexing data frames
Indexing means to selecting all/particular rows and columns of data from a DataFrame. In pandas it can be done using two constructs —
.loc() : location based
It has methods like scalar label, list of labels, slice object etc
.iloc() : Interger based
2/ Slicing data frames
In order to slice by labels you can use loc() attribute of the DataFrame.
1/ DefaultDict
In python, a dictionary is a container that holds key-value pairs. Keys must be unique, immutable objects. If you try to access or modify keys that don’t exist in the dictionary, it raise a KeyError & break up your code execution ( continued..)
2/ (Continued..)To tackle this issue,Python defaultdict type, a dictionary-like class is used.If you try to access or modify a missing key,then defaultdict will automatically create the key & generate a default value for it
A defaultdict will never raise a KeyError ( Continued..)