Apply[f, expr] or f @@ expr replaces the head of expr by f. Apply[f, expr, {1}] or f @@@ expr replaces heads at level 1 of expr by f.Apply[f, expr, levelspec] replaces heads ...

NotebookApply[notebook, data] writes data into a notebook at the current selection, replacing the first selection placeholder in data by the current selection, and then ...

MapAt[f, expr, n] applies f to the element at position n in expr. If n is negative, the position is counted from the end. MapAt[f, expr, {i, j, ...}] applies f to the part of ...

MapIndexed[f, expr] applies f to the elements of expr, giving the part specification of each element as a second argument to f. MapIndexed[f, expr, levelspec] applies f to ...

"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 ...

Since lists are just a particular kind of expression, it will come as no surprise that you can refer to parts of any expression much as you refer to parts of a list. This ...

Mathematica has many matrix operations that support operations such as building, computing, and visualizing matrices. It also has a rich language for picking out parts of ...

With careful attention to branch cuts, Mathematica supports trigonometric functions everywhere in the complex plane, with extensive exact and algebraic transformations, ...

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

Mathematica has over 3000 built-in functions and other objects, all based on a single unified framework, and all carefully designed to work together, both in simple ...