Is there a "No Units" (i.e., dimensionless) unit?

Question

I would like to be able to call the Quantity function with a null unit so that it returns the original dimensionless value. For example,

Quantity[3.0,"NoUnits"]

would return 3.0. Is there a dimensionless unit?

If it isn't there, I assume you could just add a definition to Quantity. What use of that do you have in mind? — Rojo, Commented Dec 21, 2012 at 21:34
@Rojo: I run Monte Carlo simulations which output huge quantities of data with varying dimensions, so I created a data dictionary which describes each data type, including the units. When the simulation results are loaded into Mathematica, I use the data dictionary to attach units. However, some of the data types are dimensionless and rather than having a special "dimensionless" case for the code that calls Quantity, I'd rather have Quantity handle it. — Cassini, Commented Dec 21, 2012 at 21:38

J. M.'s missing motivation · Accepted Answer · 2017-09-15 22:28:25Z

27

I believe you can use "DimensionlessUnit" to get the desired result:

Quantity[3, "DimensionlessUnit"]

(note this is the unit produced by QuantityUnit on a dimensionless value):

QuantityUnit[3]

"DimensionlessUnit"

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answered Dec 21, 2012 at 21:55

nikko

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$\begingroup$ Deleting my answer, +1 $\endgroup$
– Rojo
Commented Dec 21, 2012 at 21:58
$\begingroup$ Perfect! Thanks! $\endgroup$
– Cassini
Commented Dec 21, 2012 at 21:58
3

$\begingroup$ @Rojo: I still found your answer helpful because it forced me to (finally) learn something about unprotecting symbols. I think you should keep your answer. $\endgroup$
– Cassini
Commented Dec 21, 2012 at 22:00

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