Find the dimensions of a matrix:

Dimensions counts only dimensions at which an expression is not "ragged":

Dimensions works with arrays of any depth:

Give dimensions only down to level 2:

Dimensions works with special array types, including SparseArray objects:

SymmetrizedArray objects:

NumericArray objects:

Find the dimensions of a matrix that is a mixture of List and different special array heads:

Dimensions works with any head, not just List:

Create a version of MatrixQ that only accepts list matrices:

Create several expressions to test:

The function matrixQ gives True only for listMat, which both is a matrix and has head List:

MatrixQ gives True for matrices of any known array type:

Find dimensions of regions filled by 10 steps of cellular automaton evolution:

Dimensions always returns a list:

The default value of the option AllowedHeads allows mixtures of list, sparse and structured arrays:

It also allows any single head at successive levels:

Use AllowedHeads"ListLike" to allow any list-like array while excluding other heads:

VectorQ, MatrixQ and ArrayQ effectively use AllowedHeads"ListLike":

The setting AllowedHeads"ListLike" does not include ByteArray and NumericArray:

Combine "ListLike" with the additional heads to allow the combination:

Length[Dimensions[expr]] equals ArrayDepth[expr]:

Dimensions[Array[h,dims]] gives dims:

If Dimensions[expr] is non-empty, its first element equals Length[expr]:

Numeric expressions report dimensions based of the structure of their FullForm:

To treat all numeric expressions as scalars, use the setting List or "ListLike" for AllowedHeads: