Slicing and selection

In R, we slice objects in the following three ways:

• [: This always returns an object of the same type as the original and can be used to select more than one element.
• [[: This is used to extract elements of a list or DataFrame, and can only be used to extract a single element. The nature of the returned element will not necessarily be a list or DataFrame.
• $: This is used to extract elements of a list or DataFrame by name and is similar to [[.

Here are some slicing examples in R and their equivalents in pandas:

Comparing R-matrix and NumPy array

Let's look at creation and selection in R:

>r_mat<- matrix(2:13,4,3) 
>r_mat 
     [,1] [,2] [,3] 
[1,]    2    6   10 
[2,]    3    7   11 
[3...