QuantityQ

gives True if expr is a Quantity with valid arguments, and False otherwise.

QuantityQ[expr,dims]

gives True if expr is a Quantity with physical dimensions dims, and False otherwise.

Details

QuantityQ[expr] returns False unless expr is a Quantity expression with valid arguments (i.e. has a canonical unit).
QuantityQ[expr,dims] returns True if expr is a valid Quantity and is compatible with dims.
Dimensional specification dims may be a list of unit dimensions, a QuantityVariable, a Quantity or a string representing a quantity variable or unit dimension.

Examples

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QuantityQ tests whether an object is a Quantity with valid arguments:

Wolfram Language code: QuantityQ[Quantity[3, "Feet"]]

Wolfram Language code: QuantityQ[Quantity[3, "Foo"]]

Wolfram Language code: QuantityQ[x]

Test if an expression is a time quantity:

Wolfram Language code: QuantityQ[Quantity[300, "Second"], "Time"]

Wolfram Language code: QuantityQ[Quantity[300, "Meters"], "Time"]

Dimension specifications may be a list of unit dimensions, QuantityVariable, Quantity or string:

Wolfram Language code: QuantityQ[Quantity[300, "Meters"], {{"LengthUnit", 1}}]

Wolfram Language code: QuantityQ[Quantity[300, "Meters"], Height]

Wolfram Language code: QuantityQ[Quantity[300, "Meters"], Quantity[10, "Feet"]]

Wolfram Language code: QuantityQ[Quantity[300, "Meters"], "LengthUnit"]

Wolfram Language code: QuantityQ[Quantity[300, "Meters"], "Depth"]

QuantityQ returns False if the first argument is not a valid Quantity expression:

Wolfram Language code: QuantityQ[x, Acceleration]

QuantityQ returns False if the second argument is not a recognized dimension specification:

Wolfram Language code: QuantityQ[Quantity[3, "Meters"/"Seconds"], "foo"]

Wolfram Language code: QuantityQ[Quantity[3, "Meters"/"Seconds"], x]

QuantityQ can be used in pattern tests for functions:

Wolfram Language code: foo[x_ ? QuantityQ] := QuantityMagnitude[x] ^ 2

Wolfram Language code: foo[Quantity[8, "Feet"]]

Wolfram Language code: foo[Quantity[8, "foo"]]

QuantityQ returns False for any expression whose head is not Quantity:

Wolfram Language code: QuantityQ[2]

Wolfram Language code: QuantityQ[x]

Wolfram Language code: QuantityQ[{Quantity[7, "Weeks"], Quantity[2, "Hours"]}]

Wolfram Language code: QuantityQ[QuantityArray[{2.3, 1.5, 9.0}, "Meters"]]

Wolfram Language code: QuantityQ[QuantityVariable["V", "ElectricPotential"]]

Wolfram Language code: QuantityQ[QuantityDistribution[NormalDistribution[12, 6], "Centimeters"]]

QuantityQ returns False for Quantity expressions with invalid arguments:

Wolfram Language code: Quantity[2, x]