parmed.unit.Quantity¶

class `parmed.unit.``Quantity`(value=None, unit=None)[source]

Physical quantity, such as 1.3 meters per second.

Quantities contain both a value, such as 1.3; and a unit, such as ‘meters per second’.

Supported value types include:

1 - numbers (float, int, long) 2 - lists of numbers, e.g. [1,2,3] 3 - tuples of numbers, e.g. (1,2,3)

Note - unit conversions will cause tuples to be converted to lists

4 - lists of tuples of numbers, lists of lists of … etc. of numbers 5 - numpy.arrays

Methods

 `in_unit_system`(system) Returns a new Quantity equal to this one, expressed in a particular unit system. `in_units_of`(other_unit) Returns an equal Quantity expressed in different units. `max`(*args, **kwargs) Computes the maximum value of the sequence, with the result having the same unit as the current sequence. `mean`(*args, **kwargs) Computes the mean of a sequence, with the result having the same unit as the current sequence. `min`(*args, **kwargs) Computes the minimum value of the sequence, with the result having the same unit as the current sequence. `reduce_unit`([guide_unit]) Combine similar component units and scale, to form an equal Quantity in simpler units. `reshape`(shape[, order]) Same as numpy.ndarray.reshape, except the result is a Quantity with the same units as the current object rather than a plain numpy.ndarray `sqrt`() Returns square root of a Quantity. `std`(*args, **kwargs) Computes the square root of the variance of a sequence, with the result having the same unit as the current sequence. `sum`(*args, **kwargs) Computes the sum of a sequence, with the result having the same unit as the current sequence. `value_in_unit`(unit) Returns underlying value, in the specified units. `value_in_unit_system`(system) Returns the underlying value type, after conversion to a particular unit system.
 append count extend format index insert pop remove
`__init__`(value=None, unit=None)[source]

Create a new Quantity from a value and a unit.

Parameters
• value: (any type, usually a number) Measure of this quantity

• unit: (Unit) the physical unit, e.g. simtk.unit.meters.

Methods

 `__init__`([value, unit]) Create a new Quantity from a value and a unit. `append`(item) `count`(item) `extend`(rhs) `format`(format_spec) `in_unit_system`(system) Returns a new Quantity equal to this one, expressed in a particular unit system. `in_units_of`(other_unit) Returns an equal Quantity expressed in different units. `index`(item) `insert`(index, item) `max`(*args, **kwargs) Computes the maximum value of the sequence, with the result having the same unit as the current sequence. `mean`(*args, **kwargs) Computes the mean of a sequence, with the result having the same unit as the current sequence. `min`(*args, **kwargs) Computes the minimum value of the sequence, with the result having the same unit as the current sequence. `pop`(*args) `reduce_unit`([guide_unit]) Combine similar component units and scale, to form an equal Quantity in simpler units. `remove`(item) `reshape`(shape[, order]) Same as numpy.ndarray.reshape, except the result is a Quantity with the same units as the current object rather than a plain numpy.ndarray `sqrt`() Returns square root of a Quantity. `std`(*args, **kwargs) Computes the square root of the variance of a sequence, with the result having the same unit as the current sequence. `sum`(*args, **kwargs) Computes the sum of a sequence, with the result having the same unit as the current sequence. `value_in_unit`(unit) Returns underlying value, in the specified units. `value_in_unit_system`(system) Returns the underlying value type, after conversion to a particular unit system.