First (Built-in Mathematica Symbol)

First[expr] gives the first element in expr.

Manipulating Elements of Lists (Mathematica Tutorial)

Many of the most powerful list manipulation operations in Mathematica treat whole lists as single objects. Sometimes, however, you need to pick out or set individual elements ...

Import and Export File Elements (Mathematica How To)

Sometimes you may want to work with a specific part of a file instead of all of it. When bringing a file into Mathematica , you can elect to import just individual parts of ...

MapAll (Built-in Mathematica Symbol)

MapAll[f, expr] or f //@ expr applies f to every subexpression in expr.

Picking Out Pieces of Algebraic ... (Mathematica Tutorial)

Functions to pick out pieces of polynomials. Here is an algebraic expression. This gives the coefficient of x in e.

Getting Pieces of Lists (Mathematica Tutorial)

Picking out elements of lists. We will use this list for the examples. Here is the last element of t.

Im (Built-in Mathematica Symbol)

Im[z] gives the imaginary part of the complex number z.

Selecting Parts of Expressions with ... (Mathematica Tutorial)

"Manipulating Elements of Lists" shows how you can pick out elements of lists based on their positions. Often, however, you will need to select elements based not on where ...

StringTake (Built-in Mathematica Symbol)

StringTake["string", n] gives a string containing the first n characters in " string". StringTake["string", -n] gives the last n characters in " string". StringTake["string", ...

Manipulating Lists by Their Indices (Mathematica Tutorial)

Getting parts of lists. This gives a list of parts 1 and 3. Here is a nested list.