add unicode units (#1471)

* adds unicode units

* keep "u" and "Ohm" for compatibility
* add c, d, da and h
* lint

* py2 compatible u"" strings

pyqtgraph/units.py

@@ -1,41 +1,41 @@
 # -*- coding: utf-8 -*-
-## Very simple unit support:
+# Very simple unit support:
-##  - creates variable names like 'mV' and 'kHz'
+#  - creates variable names like 'mV' and 'kHz'
-##  - the value assigned to the variable corresponds to the scale prefix
+#  - the value assigned to the variable corresponds to the scale prefix
-##    (mV = 0.001)
+#    (mV = 0.001)
-##  - the actual units are purely cosmetic for making code clearer:
+#  - the actual units are purely cosmetic for making code clearer:
-##  
+#
-##    x = 20*pA    is identical to    x = 20*1e-12
+#    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
 
-## No unicode variable names (μ,Ω) allowed until python 3
+# All unicode identifiers get normalized automatically
-
+SI_PREFIXES = unicodedata.normalize("NFKC", u"yzafpnµm kMGTPEZY")
-SI_PREFIXES = 'yzafpnum 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(",")
-UNITS = 'm,s,g,W,J,V,A,F,T,Hz,Ohm,S,N,C,px,b,B,Pa'.split(',')
 allUnits = {}
 
-def addUnit(p, n):
+
+def addUnit(prefix, val):
     g = globals()
-    v = 1000**n
     for u in UNITS:
-        g[p+u] = v
+        g[prefix + u] = val
-        allUnits[p+u] = v
+        allUnits[prefix + u] = val
-    
-for p in SI_PREFIXES:
-    if p ==  ' ':
-        p = ''
-        n = 0
-    elif p == 'u':
-        n = -2
-    else:
-        n = SI_PREFIXES.index(p) - 8
-
-    addUnit(p, n)
-
-cm = 0.01
-
 
 
+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):
@@ -46,19 +46,19 @@ def evalUnits(unitStr):
         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
-    
-