1a71bb53c4
* adds unicode units * keep "u" and "Ohm" for compatibility * add c, d, da and h * lint * py2 compatible u"" strings
65 lines
1.6 KiB
Python
65 lines
1.6 KiB
Python
# -*- coding: utf-8 -*-
|
|
# Very simple unit support:
|
|
# - creates variable names like 'mV' and 'kHz'
|
|
# - the value assigned to the variable corresponds to the scale prefix
|
|
# (mV = 0.001)
|
|
# - the actual units are purely cosmetic for making code clearer:
|
|
#
|
|
# x = 20*pA is identical to x = 20*1e-12
|
|
#
|
|
# No unicode variable names (μ,Ω) allowed until python 3, but just assigning
|
|
# them to the globals dict doesn't error in python 2.
|
|
import unicodedata
|
|
|
|
# All unicode identifiers get normalized automatically
|
|
SI_PREFIXES = unicodedata.normalize("NFKC", u"yzafpnµm kMGTPEZY")
|
|
UNITS = unicodedata.normalize("NFKC", u"m,s,g,W,J,V,A,F,T,Hz,Ohm,Ω,S,N,C,px,b,B,Pa").split(",")
|
|
allUnits = {}
|
|
|
|
|
|
def addUnit(prefix, val):
|
|
g = globals()
|
|
for u in UNITS:
|
|
g[prefix + u] = val
|
|
allUnits[prefix + u] = val
|
|
|
|
|
|
for pre in SI_PREFIXES:
|
|
v = SI_PREFIXES.index(pre) - 8
|
|
if pre == " ":
|
|
pre = ""
|
|
addUnit(pre, 1000 ** v)
|
|
|
|
addUnit("c", 0.01)
|
|
addUnit("d", 0.1)
|
|
addUnit("da", 10)
|
|
addUnit("h", 100)
|
|
# py2 compatibility
|
|
addUnit("u", 1e-6)
|
|
|
|
|
|
def evalUnits(unitStr):
|
|
"""
|
|
Evaluate a unit string into ([numerators,...], [denominators,...])
|
|
Examples:
|
|
N m/s^2 => ([N, m], [s, s])
|
|
A*s / V => ([A, s], [V,])
|
|
"""
|
|
pass
|
|
|
|
|
|
def formatUnits(units):
|
|
"""
|
|
Format a unit specification ([numerators,...], [denominators,...])
|
|
into a string (this is the inverse of evalUnits)
|
|
"""
|
|
pass
|
|
|
|
|
|
def simplify(units):
|
|
"""
|
|
Cancel units that appear in both numerator and denominator, then attempt to replace
|
|
groups of units with single units where possible (ie, J/s => W)
|
|
"""
|
|
pass
|