147 lines
3.4 KiB
Python
147 lines
3.4 KiB
Python
# _*_ coding:utf-8 _*_
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"""
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This file contains a set of functions for matching values which may be written in different formats
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e.g.
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0.1uF = 100n (different suffix specified, one has missing unit)
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0R1 = 0.1Ohm (Unit replaces decimal, different units)
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"""
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import re
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PREFIX_MICRO = [u"μ","u","micro"]
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PREFIX_MILLI = ["milli","m"]
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PREFIX_NANO = ["nano","n"]
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PREFIX_PICO = ["pico","p"]
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PREFIX_KILO = ["kilo","k"]
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PREFIX_MEGA = ["mega","meg"]
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PREFIX_GIGA = ["giga","g"]
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#All prefices
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PREFIX_ALL = PREFIX_PICO + PREFIX_NANO + PREFIX_MICRO + PREFIX_MILLI + PREFIX_KILO + PREFIX_MEGA + PREFIX_GIGA
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#Common methods of expressing component units
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UNIT_R = ["r","ohms","ohm",u"Ω"]
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UNIT_C = ["farad","f"]
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UNIT_L = ["henry","h"]
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UNIT_ALL = UNIT_R + UNIT_C + UNIT_L
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"""
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Return a simplified version of a units string, for comparison purposes
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"""
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def getUnit(unit):
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if not unit: return None
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unit = unit.lower()
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if unit in UNIT_R: return "R"
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if unit in UNIT_C: return "F"
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if unit in UNIT_L: return "H"
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return None
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"""
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Return the (numerical) value of a given prefix
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"""
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def getPrefix(prefix):
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if not prefix: return 1
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prefix = prefix.lower()
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if prefix in PREFIX_PICO: return 1.0e-12
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if prefix in PREFIX_NANO: return 1.0e-9
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if prefix in PREFIX_MICRO: return 1.0e-6
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if prefix in PREFIX_MILLI: return 1.0e-3
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if prefix in PREFIX_KILO: return 1.0e3
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if prefix in PREFIX_MEGA: return 1.0e6
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if prefix in PREFIX_GIGA: return 1.0e9
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return 1
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def groupString(group): #return a reg-ex string for a list of values
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return "|".join(group)
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def matchString():
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return "^([0-9\.]+)(" + groupString(PREFIX_ALL) + ")*(" + groupString(UNIT_ALL) + ")*(\d*)$"
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"""
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Return a normalized value and units for a given component value string
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e.g. compMatch("10R2") returns (10, R)
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e.g. compMatch("3.3mOhm") returns (0.0033, R)
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"""
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def compMatch(component):
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#remove any commas
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component = component.strip().replace(",","").lower()
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match = matchString()
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result = re.search(match, component)
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if not result: return None
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if not len(result.groups()) == 4: return None
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value,prefix,units,post = result.groups()
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#special case where units is in the middle of the string
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#e.g. "0R05" for 0.05Ohm
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#in this case, we will NOT have a decimal
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#we will also have a trailing number
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if post and "." not in value:
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try:
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value = float(int(value))
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postValue = float(int(post)) / (10 ** len(post))
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value = value * 1.0 + postValue
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except:
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return None
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try:
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val = float(value)
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except:
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return None
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val = "{0:.15f}".format(val * 1.0 * getPrefix(prefix))
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return (val, getUnit(units))
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def componentValue(valString):
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result = compMatch(valString)
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if not result:
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return valString #return the same string back
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if not len(result) == 2: #result length is incorrect
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return valString
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(val, unit) = result
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return val
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#compare two values
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def compareValues(c1, c2):
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r1 = compMatch(c1)
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r2 = compMatch(c2)
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if not r1 or not r2: return False
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(v1, u1) = r1
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(v2, u2) = r2
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if v1 == v2:
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#values match
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if u1 == u2: return True #units match
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if not u1: return True #no units for component 1
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if not u2: return True #no units for component 2
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return False
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