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 ):

In[256]:=
Click for copyable input
Out[256]=

Use Part to pick the third element of the list:

In[257]:=
Click for copyable input
Out[257]=

Or use (the short form notation for Part):

In[258]:=
Click for copyable input
Out[258]=

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

In[259]:=
Click for copyable input
Out[259]=

Pick out elements 5 through 8 of the list:

In[260]:=
Click for copyable input
Out[260]=

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

In[261]:=
Click for copyable input
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:

In[262]:=
Click for copyable input
Out[262]=

Use MatrixForm to see it laid out as a matrix:

In[263]:=
Click for copyable input
Out[263]//MatrixForm=

The first part of the matrix is the first row:

In[264]:=
Click for copyable input
Out[264]=
New to Mathematica? Find your learning path »
Have a question? Ask support »