Author: bugman
Date: Thu Aug 28 11:35:37 2014
New Revision: 25375
URL: http://svn.gna.org/viewcvs/relax?rev=25375&view=rev
Log:
Implemented the lib.periodic_table.periodic_table.atomic_weight() method.
This returns the standard atomic weight of the atom as a float.
Modified:
trunk/lib/periodic_table.py
Modified: trunk/lib/periodic_table.py
URL:
http://svn.gna.org/viewcvs/relax/trunk/lib/periodic_table.py?rev=25375&r1=25374&r2=25375&view=diff
==============================================================================
--- trunk/lib/periodic_table.py (original)
+++ trunk/lib/periodic_table.py Thu Aug 28 11:35:37 2014
@@ -27,6 +27,9 @@
- Atomic weights of the elements 2011 (IUPAC Technical Report) (U{DOI:
10.1351/PAC-REP-13-03-02<http://dx.doi.org/10.1351/PAC-REP-13-03-02>).
"""
+# Python module imports.
+from numpy import array, average, float64
+
# relax module imports.
from lib.errors import RelaxError
@@ -40,7 +43,7 @@
# Initialise some data structures.
self.symbol = []
self.name = []
- self.atomic_weights = []
+ self.atomic_weights = {}
def _add(self, atomic_number=None, symbol=None, name=None,
atomic_weight=None):
@@ -63,7 +66,40 @@
# Append the values.
self.symbol.append(symbol)
self.name.append(name)
- self.atomic_weights.append(atomic_weight)
+ self.atomic_weights[symbol] = atomic_weight
+
+
+ def atomic_weight(self, symbol=None):
+ """Return the standard atomic weight as a float for the given atom.
+
+ @keyword symbol: The atomic symbol.
+ @type symbol: str
+ @return: The standard atomic weight.
+ @rtype: float
+ """
+
+ # Checks.
+ if symbol not in self.atomic_weights:
+ raise RelaxError("The atomic symbol '%s' is unknown." % symbol)
+
+ # The weight.
+ weight = self.atomic_weights[symbol]
+
+ # A range, or an unstable isotope.
+ if weight[0] == '[':
+ # Convert to a list.
+ vals = eval(weight)
+
+ # Use numpy to average the list, assuming equal weighting.
+ return average(array(vals, float64))
+
+ # A weight with uncertainty.
+ else:
+ # Obtain the first part of the number.
+ val = weight.split('(')[0]
+
+ # Convert to a float and return the value.
+ return float(val)
def lookup_symbol(self, atomic_number=None):
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