QuantityArray
QuantityArray[mags,unit]
represents an array of quantities with magnitudes mags and common unit.
QuantityArray[mags,{unit1,unit2,…}]
represents an array of lists of quantities with units {unit1,unit2,…}.
QuantityArray[quants]
converts an array of Quantity objects into a single QuantityArray object.
Details
- QuantityArray[…] is converted to a structured array expression of the form QuantityArray[StructuredData[dims,{mags,…}]].
- In QuantityArray[mags,unit], the array of magnitudes mags can be a full array of any depth and dimensions.
- In QuantityArray[mags,{unit1,unit2,…}], the length of the list of uniti must coincide with the deepest dimension of mags.
- In QuantityArray[mags,…], mags can be a SparseArray object.
- Normal converts QuantityArray objects to arrays of Quantity objects. To avoid normalization of other structures, like SparseArray or dimensionless Quantity objects, use Normal[qa,QuantityArray]. »
Examples
open allclose allBasic Examples (3)
A list of lengths, all given in meters:
Extract its magnitudes and units separately:
A list of pairs {time,length}:
Extract its magnitudes and units separately:
Convert a normal array of quantities into a QuantityArray representation:
Scope (6)
Construct an array of quantities with the same unit:
Convert a normal array of quantities with the same unit:
Construct an array of tuples of quantities with different units:
Convert a normal matrix of quantities with the same units in each column:
Construct an array of matrices of quantities with different units:
Convert a normal matrix of quantities with the same units in each subarray:
Construct an array of quantities with IndependentUnit specifications:
Convert an array of Quantity objects into a QuantityArray expression:
QuantityArray objects include properties that give information about the array:
The "Summary" property gives a brief summary of information about the array:
The "StructuredAlgorithms" property gives a list of functions that have algorithms that use the structure of the representation:
The array of magnitudes and the elementary block of units can be extracted using properties:
Properties & Relations (8)
A QuantityArray object is interpreted as an array of Quantity objects:
It is a list of pairs; hence, a matrix, not a vector:
It is an array of Quantity objects, not an array of numbers:
The QuantityArray representation is memory efficient:
It uses only 6% of the memory of the corresponding normal representation:
It also allows faster extraction of magnitudes and units:
Compare to the slower extraction from the normal array of quantities:
A single quantity is automatically converted into a Quantity object:
This is a list with one quantity:
During conversion, QuantityArray does not try to change units:
UnitConvert will unify the units:
The QuantityArray structure is preserved in multiple operations. Take two arrays:
Addition of QuantityArray objects of compatible units, automatically converting some of them:
Multiplication of QuantityArray objects of compatible dimensions:
Tensor product of QuantityArray objects:
Transposition is special because it stores the permutation:
Flattening is also special in that sense:
The result is an equivalent representation of the original quantity array:
Take a QuantityArray object with compatible but different units:
CommonUnits will convert it into a single unit array:
To select the unit, use UnitConvert:
A QuantityArray object of infinite precision:
The arithmetic operations take precision into account:
QuantityArray will automatically attempt to interpret an unknown unit string:
Possible Issues (1)
Normalization of QuantityArray objects also normalizes purely numerical quantities such as percents:
Specify that only the QuantityArray structure should be normalized:
Text
Wolfram Research (2015), QuantityArray, Wolfram Language function, https://reference.wolfram.com/language/ref/QuantityArray.html (updated 2020).
CMS
Wolfram Language. 2015. "QuantityArray." Wolfram Language & System Documentation Center. Wolfram Research. Last Modified 2020. https://reference.wolfram.com/language/ref/QuantityArray.html.
APA
Wolfram Language. (2015). QuantityArray. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/QuantityArray.html