pq-ipython.rst

Using PhysicalQuantities in IPython

The IPython extension makes using physical quantities easier. To load the extension use:

>>> %load_ext PhysicalQuantities.ipython

Now entering a physical quantities gets very easy:

>>> d = 2.3 s**3
>>> print("d = %s" %d)
d = 2.3 s^3
>>> t = 3 A
>>> print("t = %s" %t)
t = 3 A
>>> v = 2.3e3 * d / t
>>> print("v = %s" %v)
v = 1763.3333333333333 s^3/A

Unit conversion

The easiest way to scale a unit is to use prefix attributes:

>>> u = 1 V
>>> print(u)
1 V
>>> print(u.mV)
1000.0 mV
>>> print(u.uV)
1000000.0 uV

To convert between different representations of a unit, to() can be used:

>>> a = 1 N * 1 m
>>> print(a)
1 m*N
>>> print(a.to('J'))
1.0 J

Using other value types

The PhysicalQuantity class tries to be a wrapper around the value of a given quantity, i.e. not only single numbers can be used. For examples using Numpy arrays, take a look at the Using Numpy Arrays notebook.

>>> u = (1 + 1j) * 1V
>>> print("u = %s" %u)
u = (1+1j) V
>>> u = [1,2,3] * 1V
>>> print("u = %s" %u)
u = [1, 2, 3] V
>>> a = [1, 2, 3] * 1V
>>> a

$[1, 2, 3] $\text{V}$

>>> a.value
[1, 2, 3]
>>> 2*a

[1, 2, 3, 1, 2, 3]V

List of all defined Units:

All predefined units can be listed using the list() or html_list() function of a unit:

>>> from PhysicalQuantities import units_html_list
>>> units_html_list()

Name	Base Unit	Quantity
Wb	1.0 $\frac{\text{m}^{2}\cdot \text{kg}}{\text{A}\cdot \text{s}^2}$	Weber
s	1.0 $\text{s}$	Second
h	3600.0 $\text{s}$	Hour
lx	1.0 $\frac{\text{cd}\cdot \text{sr}}{\text{m}^2}$	Lux
sr	1.0 $\text{sr}$	Streradian
min	60.0 $\text{s}$	Minute
J	1.0 $\frac{\text{m}^{2}\cdot \text{kg}}{\text{s}^2}$	Joule
Pa	1.0 $\frac{\text{kg}}{\text{m}\cdot \text{s}^2}$	Pascal
arcsec	4.84813681109536e-06 $\text{rad}$	seconds of arc
cd	1.0 $\text{cd}$	Candela
lm	1.0 $\text{cd}\cdot \text{sr}$	Lumen
H	1.0 $\frac{\text{m}^{2}\cdot \text{kg}}{\text{A}^2\cdot \text{s}^2}$	Henry
m	1.0 $\text{m}$	Metre
T	1.0 $\frac{\text{kg}}{\text{A}\cdot \text{s}^2}$	Tesla
S	1.0 $\frac{\text{A}^{2}\cdot \text{s}^{3}}{\text{m}^2\cdot \text{kg}}$	Siemens
C	1.0 $\text{A}\cdot \text{s}$	Coulomb
deg	0.017453292519943295 $\text{rad}$	Degree
K	1.0 $\text{K}$	Kelvin
g	0.001 $\text{kg}$	Gram
kg	1 $\text{kg}$	Kilogram
F	1.0 $\frac{\text{A}^{2}\cdot \text{s}^{4}}{\text{m}^2\cdot \text{kg}}$	Farad
W	1.0 $\frac{\text{m}^{2}\cdot \text{kg}}{\text{s}^3}$	Watt
arcmin	0.0002908882086657216 $\text{rad}$	minutes of arc
Hz	1.0 $\frac{1}{\text{s}}$	Hertz
A	1.0 $\text{A}$	Ampere
Ohm	1.0 $\frac{\text{m}^{2}\cdot \text{kg}}{\text{A}^2\cdot \text{s}^3}$	Ohm
N	1.0 $\frac{\text{m}\cdot \text{kg}}{\text{s}^2}$	Newton
V	1.0 $\frac{\text{m}^{2}\cdot \text{kg}}{\text{A}\cdot \text{s}^3}$	Volt
rad	1.0 $\text{rad}$	Radian
mol	1.0 $\text{mol}$	Mol