added API and CLI for ppp-mer conversion

salamanca/cli.py

@@ -76,13 +76,68 @@ def exchange(**kwargs):
     print(ret)
     return ret
 
+
 COMMANDS['exchange'] = (
     """Exchange currency from one country/year to another.""",
     exchange_cli,
     exchange,
 )
 
 
+def to_ppp_cli(parser):
+    amt = 'quantity of currency in MER (default: 1.0)'
+    parser.add_argument('-x', '--amt', help=amt, type=float, default=1.0)
+    iso = '3-letter ISO code for the country'
+    parser.add_argument('--iso', help=iso)
+    year = 'year of conversion'
+    parser.add_argument('--year', type=int, help=year)
+
+
+def to_ppp(**kwargs):
+    amt = kwargs['amt']
+    iso = kwargs['iso']
+    year = kwargs['year']
+
+    xlator = currency.Translator()
+    ret = amt * xlator.mer_to_ppp(iso, year)
+    print(ret)
+    return ret
+
+
+COMMANDS['to_ppp'] = (
+    """Exchange currency in MER to PPP.""",
+    to_ppp_cli,
+    to_ppp,
+)
+
+
+def to_mer_cli(parser):
+    amt = 'quantity of currency in PPP (default: 1.0)'
+    parser.add_argument('-x', '--amt', help=amt, type=float, default=1.0)
+    iso = '3-letter ISO code for the country'
+    parser.add_argument('--iso', help=iso)
+    year = 'year of conversion'
+    parser.add_argument('--year', type=int, help=year)
+
+
+def to_mer(**kwargs):
+    amt = kwargs['amt']
+    iso = kwargs['iso']
+    year = int(kwargs['year'])
+
+    xlator = currency.Translator()
+    ret = amt / xlator.mer_to_ppp(iso, year)
+    print(ret)
+    return ret
+
+
+COMMANDS['to_mer'] = (
+    """Exchange currency in PPP to MER.""",
+    to_mer_cli,
+    to_mer,
+)
+
+
 def main():
     descr = """
     Main CLI for salamanca.

salamanca/currency.py

@@ -48,6 +48,12 @@ def inflation(self, iso, fromyr, toyr, method='deflator'):
             x = self.inflation('USA', fromyr, toyr, method=method)
         return x
 
+    def ppp_to_mer(self, iso, yr):
+        return self._ppp_to_mer.loc[iso][yr]
+
+    def mer_to_ppp(self, iso, yr):
+        return 1.0 / self._ppp_to_mer.loc[iso][yr]
+
     def exchange(self, x, iso=None, yr=None, units='MER',
                  fromiso=None, fromyr=None,
                  toiso=None, toyr=None,

salamanca/data.py

@@ -16,7 +16,7 @@
 
 WB_INDICATORS = {
     'SP.POP.TOTL': 'total_population',
-    'PA.NUS.PPPC.RF': 'ppp_to_mer',
+    'PA.NUS.PPPC.RF': 'ppp_to_mer',  # conversion factor [PPP / MER]
     'FP.CPI.TOTL': 'cpi',
     'PA.NUS.FCRF': 'exchange_rate',
     'NY.GDP.DEFL.ZS': 'gdp_deflator',