Move numeric sort to the util module.

Also convert the list-sorting function to a more general
key-generating function.

Author: pavoljuhas

diffpy/srfit/fitbase/fitresults.py

@@ -28,6 +28,7 @@
 
 from diffpy.srfit.util.inpututils import inputToString
 from diffpy.srfit.util import _DASHEDLINE
+from diffpy.srfit.util import sortKeyForNumericString as numstr
 
 
 class FitResults(object):
@@ -347,7 +348,7 @@ def formatResults(self, header = "", footer = "", update = False):
         ## Per-FitContribution results
         if len(self.conresults) > 1:
             keys = self.conresults.keys()
-            numericStringSort(keys)
+            keys.sort(key=numstr)
 
             lines.append("")
             l = "Contributions"
@@ -428,7 +429,7 @@ def formatResults(self, header = "", footer = "", update = False):
                     keys.append(name)
                     vals[name] = (val, unc)
 
-            numericStringSort(keys)
+            keys.sort(key=numstr)
             w = str(w+1)
             formatstr = "%-"+w+"s %- 15f +/- %-15f"
             for name in keys:
@@ -669,23 +670,3 @@ def initializeRecipe(recipe, results):
             var.value = float(value)
 
     return
-
-
-def numericStringSort(lst):
-    """Sort list of strings inplace according to general numeric value.
-
-    Each string gets split to string and integer segments to create keys
-    for comparison.  Signs, decimal points and exponents are ignored.
-
-    lst  -- sorted list of strings
-
-    No return value to highlight inplace sorting.
-
-    """
-    rx = re.compile(r'(\d+)')
-    keys = [ rx.split(s) for s in lst ]
-    for k in keys:  k[1::2] = [ int(i) for i in k[1::2] ]
-    newlst = zip(keys, lst)
-    newlst.sort()
-    lst[:] = [kv[1] for kv in newlst]
-    return

diffpy/srfit/util/__init__.py

@@ -20,4 +20,34 @@
 
 _DASHEDLINE = 78 * '-'
 
+
+def sortKeyForNumericString(s):
+    """\
+    Compute key for sorting strings according to their integer numeric value.
+
+    Each string gets split to string and integer segments to create keys
+    for comparison.  Signs, decimal points and exponents are ignored.
+    This function is intended as the ``key`` argument for the ``sorted``
+    or ``list.sort`` function.
+
+    Parameters
+    ----------
+    s : str
+        String which may have numeric components, e.g., "a12b".
+
+    Returns
+    -------
+    tuple
+        Tuple of non-numeric segments intermixed with integer values.
+    """
+    if sortKeyForNumericString._rx is None:
+        import re
+        sortKeyForNumericString._rx = re.compile(r'(\d+)')
+    rx = sortKeyForNumericString._rx
+    rv = tuple((int(w) if i % 2 else w)
+               for i, w in enumerate(rx.split(s)))
+    return rv
+
+sortKeyForNumericString._rx = None
+
 # End of file