MATHEMATICA HOW TO

# How to | Get Elements of Lists

Lists are very important structures in Mathematica. Lists allow you to treat any kind of collection of objects as a single entity. Sometimes you need to pick out or extract individual elements or groups of elements from a list.

Set up a list of the first 10 squares (stored as ):

 Out[256]=

Use Part to pick the third element of the list:

 Out[257]=

Or use (the short form notation for Part):

 Out[258]=

Combine (the short form for Span) with Part to pick out the elements from 1 to 5:

 Out[259]=

Pick out elements 5 through 8 of the list:

 Out[260]=

Pick the last 7 elements (negative indices count from the end):

 Out[261]=

A matrix in Mathematica is a list of lists of the same length. You can pick out elements from a matrix just like you would from a list.

Set up a 5×5 matrix of integers:

 Out[262]=

Use MatrixForm to see it laid out as a matrix:

 Out[263]//MatrixForm=

The first part of the matrix is the first row:

 Out[264]=