Allow currency symbols to be given after the number, as is common pra…

…ctice in some regions

doc/examples.rst

@@ -915,3 +915,63 @@ If you do, the output of the script looks like this::
 A more sophisticated version of `cryptocurrency 
 <https://github.com/KenKundert/cryptocurrency/blob/master/cryptocurrency>`_
 this example can be found on GitHub.
+
+
+.. bitcoin example {{{1
+
+Dynamic Unit Conversions
+------------------------
+
+Normally unit conversions are static, meaning that once the conversion values 
+are set they do not change during the life of the process.  However, that need 
+not be true if functions are used to perform the conversion.  In the following 
+example, the current price of Bitcoin is queried from a price service and used 
+in the conversion.  The price service is queried each time a conversion is 
+performed, so it is always up-to-date, no longer how long the program runs.
+
+.. code-block:: python
+
+    #!/usr/bin/env python3
+
+    # Bitcoin
+    # This example demonstrates how to use UnitConversion to convert between 
+    # bitcoin and dollars at the current price.
+
+    from quantiphy import Quantity, UnitConversion
+    import requests
+
+    # get the current bitcoin price from coingecko.com
+    url = 'https://api.coingecko.com/api/v3/simple/price'
+    params = dict(ids='bitcoin', vs_currencies='usd')
+    def get_btc_price():
+        try:
+            resp = requests.get(url=url, params=params)
+            prices = resp.json()
+            return prices['bitcoin']['usd']
+        except Exception as e:
+            print('error: cannot connect to coingecko.com.')
+
+    # use UnitConversion from QuantiPhy to perform the conversion
+    bitcoin_units = ['BTC', 'btc', 'Ƀ', '₿']
+    satoshi_units = ['sat', 'sats', 'ș']
+    dollar_units = ['USD', 'usd', '$']
+    UnitConversion(
+        dollar_units, bitcoin_units,
+        lambda b: b*get_btc_price(), lambda d: d/get_btc_price()
+    )
+    UnitConversion(satoshi_units, bitcoin_units, 1e8)
+    UnitConversion(
+        dollar_units, satoshi_units,
+        lambda s: s*get_btc_price()/1e8, lambda d: d/(get_btc_price()/1e8),
+    )
+
+    unit_btc = Quantity('1 BTC')
+    unit_dollar = Quantity('$1')
+
+    print(f'{unit_btc:>8,.2p} = {unit_btc:,.2p$}')
+    print(f'{unit_dollar:>8,.2p} = {unit_dollar:,.0psat}')
+
+When run, the script prints something like this:
+
+   1 BTC = $46,007
+      $1 = 2,174 sat

doc/releases.rst

@@ -8,8 +8,11 @@ Latest development release
 | Version: 2.16.1
 | Released: 2021-12-23
 
+- Refine the list of currency symbols.
+- Allows currency symbols to be given before or after the underlying number.
 - Allow :class:`Quantity` subclasses to be used in scaling if they have units.
 
+
 2.16 (2021-12-14)
 -----------------
 - Add support for — as comment character and make it the default.

doc/user.rst

@@ -546,7 +546,7 @@ QuantiPhy* provides a collection of pre-defined converters for common units:
 
 ====== ================================================================
 K:     K, F °F, R °R
-C, °C: K, C °C, F °F, R °R
+C °C:  K, C °C, F °F, R °R
 m:     km, m, cm, mm, um μm micron, nm, Å angstrom, mi mile miles,
        in inch inches
 g:     oz, lb lbs

quantiphy.py

@@ -428,12 +428,12 @@ def add_constant(value, alias=None, unit_systems=None):
     # These must be given in order, one for every three decades.
 
 # Supported currency symbols (these go on left side of number)
-CURRENCY_SYMBOLS = '$€¥£₩₺₽₹ɃΞȄ'
+CURRENCY_SYMBOLS = '$€¥£₩₺₽₹Ƀ₿Ξ'
 
 # Unit symbols that are not simple letters.
 # Do not include % as it will be picked up when converting text to numbers,
 # which is generally not desired (you would end up converting 0.001% to 1m%).
-UNIT_SYMBOLS = '°ÅΩƱΩ℧'
+UNIT_SYMBOLS = '°ÅΩƱΩ℧¢$€¥£₩₺₽₹Ƀ₿șΞ'
 
 # Regular expression for recognizing and decomposing string .format method codes
 FORMAT_SPEC = re.compile(r'''\A
@@ -446,7 +446,7 @@ def add_constant(value, alias=None, unit_systems=None):
         ([qpPQrRbBusSeEfFgGdn])         # format
         ([a-zA-Z%{us}{cs}][-^/()\w]*)?  # units
     )?
-\Z'''.format(cs=CURRENCY_SYMBOLS, us=UNIT_SYMBOLS), re.VERBOSE)
+\Z'''.format(cs=re.escape(CURRENCY_SYMBOLS), us=re.escape(UNIT_SYMBOLS)), re.VERBOSE)
 
 # Defaults {{{1
 DEFAULTS = dict(
@@ -1244,8 +1244,8 @@ def fix_sign(num):
         currency = _named_regex('currency', '[%s]' % CURRENCY_SYMBOLS)
         units = _named_regex(
             r'units', r'(?:[a-zA-Z%√{us}{cur}][-^/()\w·⁻⁰¹²³⁴⁵⁶⁷⁸⁹√{us}{cur}]*)?'.format(
-                us = UNIT_SYMBOLS,
-                cur = CURRENCY_SYMBOLS,
+                us = re.escape(UNIT_SYMBOLS),
+                cur = re.escape(CURRENCY_SYMBOLS),
             )
             # examples: Ohms, V/A, J-s, m/s^2, H/(m-s), Ω, %, m·s⁻², V/√Hz
             # leading char must be letter to avoid 1.0E-9s -> (1e18, '-9s')
@@ -1391,10 +1391,10 @@ def fix_sign(num):
         ]
 
         # numbers embedded in text {{{3
-        smpl_units = '[a-zA-Z_{us}]*'.format(us=UNIT_SYMBOLS)
+        smpl_units = '[a-zA-Z_{us}]*'.format(us=re.escape(UNIT_SYMBOLS))
             # may only contain alphabetic characters, ex: V, A, _Ohms, etc.
             # or obvious unicode units, ex: °ÅΩƱ
-        sf_or_units = '[a-zA-Z_µ{us}]+'.format(us=UNIT_SYMBOLS)
+        sf_or_units = '[a-zA-Z_µ{us}]+'.format(us=re.escape(UNIT_SYMBOLS))
             # must match units or scale factors: add µ, make non-optional
         space = '[   ]?'  # optional non-breaking space (do not use a normal space)
         left_delimit = r'(?:\A|(?<=[^a-zA-Z0-9_.]))'

tests/test_quantity.nt

@@ -1,6 +1,6 @@
 test_number_recognition:
 
-    # some simple cases
+    # some simple cases {{{1
     grange:
         given: q = Quantity(0)
         tests:
@@ -111,7 +111,7 @@ test_number_recognition:
                 evaluate: str(q)
                 expected: '2 s'
 
-    # test all the scale factors
+    # test all the scale factors {{{1
     quill:
         given: q = Quantity('1ys')
         tests:
@@ -323,7 +323,7 @@ test_number_recognition:
                 expected: '1e24 s'
 
 
-    # test zero
+    # test zero {{{1
     nickel:
         given: q = Quantity('0ns')
         tests:
@@ -549,7 +549,7 @@ test_number_recognition:
                 expected: '0 s'
 
 
-    # test various forms of the mantissa when using scale factors
+    # test various forms of the mantissa when using scale factors {{{1
     delicacy:
         given: q = Quantity('1ns')
         tests:
@@ -831,7 +831,7 @@ test_number_recognition:
                 expected: '100 ns'
 
 
-    # test various forms of the mantissa when using exponents
+    # test various forms of the mantissa when using exponents {{{1
     hairpiece:
         given: q = Quantity('1e-9s')
         tests:
@@ -1103,7 +1103,7 @@ test_number_recognition:
                 expected: '-100 ps'
 
 
-    # test various forms of the mantissa alone
+    # test various forms of the mantissa alone {{{1
     educate:
         given: q = Quantity('100000.0s')
         tests:
@@ -1325,7 +1325,7 @@ test_number_recognition:
                 expected: '10 us'
 
 
-    # test various forms of units
+    # test various forms of units {{{1
     impute:
         given: q = Quantity('1nΩ')
         tests:
@@ -1575,7 +1575,7 @@ test_number_recognition:
                 expected: '1 nm·s⁻²'
 
 
-    # test currency
+    # test currency {{{1
     bishop:
         given: q = Quantity('$10K')
         tests:
@@ -1817,8 +1817,68 @@ test_number_recognition:
                 evaluate: q.fixed(prec=2, strip_zeros=True, strip_radix=True)
                 expected: '$100'
 
+    retina:
+        given: q = Quantity('Ƀ1.4')
+        tests:
+            tendon:
+                evaluate: q.as_tuple()
+                expected: (1.4, 'Ƀ')
+            recover:
+                evaluate: str(q)
+                expected: 'Ƀ1.4'
+
+    curly:
+        given: q = Quantity('₿1.4')
+        tests:
+            tendon:
+                evaluate: q.as_tuple()
+                expected: (1.4, '₿')
+            recover:
+                evaluate: str(q)
+                expected: '₿1.4'
+
+    blaze:
+        given: q = Quantity('1.4 ș')
+        tests:
+            tendon:
+                evaluate: q.as_tuple()
+                expected: (1.4, 'ș')
+            recover:
+                evaluate: str(q)
+                expected: '1.4 ș'
+
+    splendor:
+        given: q = Quantity('1.4 ¢')
+        tests:
+            tendon:
+                evaluate: q.as_tuple()
+                expected: (1.4, '¢')
+            recover:
+                evaluate: str(q)
+                expected: '1.4 ¢'
+
+    brassy:
+        given: q = Quantity('1.4Ƀ')
+        tests:
+            tendon:
+                evaluate: q.as_tuple()
+                expected: (1.4, 'Ƀ')
+            recover:
+                evaluate: str(q)
+                expected: 'Ƀ1.4'
+
+    backlog:
+        given: q = Quantity('1.4 ₿')
+        tests:
+            tendon:
+                evaluate: q.as_tuple()
+                expected: (1.4, '₿')
+            recover:
+                evaluate: str(q)
+                expected: '₿1.4'
+
 
-    # test unusual numbers
+    # test unusual numbers {{{1
     sheathe:
         given: q = Quantity('inf')
         tests:
@@ -2244,7 +2304,7 @@ test_number_recognition:
                 expected: '$100M'
 
 
-    # test full precision
+    # test full precision {{{1
     fiery:
         given: q = Quantity('3.14159265ns')
         tests:
@@ -2526,7 +2586,7 @@ test_number_recognition:
                 expected: '31.415926500 fs'
 
 
-    # test preferences
+    # test preferences {{{1
     chestnut:
         given: q = Quantity('1 ns')
         tests:
@@ -2961,7 +3021,7 @@ test_number_recognition:
                 expected: '−4.7 kΩ'
 
 
-    # test constants
+    # test constants {{{1
     neuron:
         given: q = Quantity('h')
         tests:
@@ -3343,7 +3403,7 @@ test_number_recognition:
                 evaluate: f'{q:S}'
                 expected: "Z₀ = 376.73 Ohms"
 
-    # test scaling
+    # test scaling {{{1
     segregate:
         given: q = Quantity(2, scale=(1000, 'g'))
         tests: