Consistent handling of by/field arguments for plot.py and summary.py

Now both scripts also fallback to guessing what fields to use based on
what fields can be converted to integers. This is more falible, and
doesn't work for tests/benchmarks, but in those cases explicit fields
can be used (which is what would be needed without guessing anyways).

scripts/plot.py

@@ -330,12 +330,13 @@ def collect(csv_paths, renames=[]):
 
     return results
 
-def dataset(results, x=None, y=None, defines={}):
+def dataset(results, x=None, y=None, define=[]):
     # organize by 'by', x, and y
     dataset = {}
-    for i, r in enumerate(results):
+    i = 0
+    for r in results:
         # filter results by matching defines
-        if not all(k in r and r[k] in vs for k, vs in defines.items()):
+        if not all(k in r and r[k] in vs for k, vs in define):
             continue
 
         # find xs
@@ -348,6 +349,7 @@ def dataset(results, x=None, y=None, defines={}):
                 continue
         else:
             x_ = i
+            i += 1
 
         # find ys
         if y is not None:
@@ -368,14 +370,29 @@ def dataset(results, x=None, y=None, defines={}):
 
     return dataset
 
-def datasets(results, by=None, x=None, y=None, defines={}):
+def datasets(results, by=None, x=None, y=None, define=[]):
     # filter results by matching defines
     results_ = []
     for r in results:
-        if all(k in r and r[k] in vs for k, vs in defines.items()):
+        if all(k in r and r[k] in vs for k, vs in define):
             results_.append(r)
     results = results_
 
+    # if y not specified, try to guess from data
+    if y is None:
+        y = co.OrderedDict()
+        for r in results:
+            for k, v in r.items():
+                if by is not None and k in by:
+                    continue
+                if y.get(k, True):
+                    try:
+                        dat(v)
+                        y[k] = True
+                    except ValueError:
+                        y[k] = False
+        y = list(k for k,v in y.items() if v)
+
     if by is not None:
         # find all 'by' values
         ks = set()
@@ -387,13 +404,17 @@ def datasets(results, by=None, x=None, y=None, defines={}):
     datasets = co.OrderedDict()
     for ks_ in (ks if by is not None else [()]):
         for x_ in (x if x is not None else [None]):
-            for y_ in (y if y is not None else [None]):
-                datasets[ks_ + (x_, y_)] = dataset(
+            for y_ in y:
+                # hide x/y if there is only one field
+                k_x = x_ if len(x or []) > 1 else ''
+                k_y = y_ if len(y or []) > 1 else ''
+
+                datasets[ks_ + (k_x, k_y)] = dataset(
                     results,
                     x_,
                     y_,
-                    {by_: {k_} for by_, k_ in zip(by, ks_)}
-                        if by is not None else {})
+                    [(by_, k_) for by_, k_ in zip(by, ks_)]
+                        if by is not None else [])
 
     return datasets
     
@@ -431,7 +452,7 @@ def main(csv_paths, *,
     if ylim is not None and len(ylim) == 1:
         ylim = (0, ylim[0])
 
-    # seperate out renames
+    # separate out renames
     renames = [k.split('=', 1)
         for k in it.chain(by or [], x or [], y or [])
         if '=' in k]
@@ -452,7 +473,7 @@ def main(csv_paths, *,
         results = collect(csv_paths, renames)
 
         # then extract the requested datasets
-        datasets_ = datasets(results, by, x, y, dict(define))
+        datasets_ = datasets(results, by, x, y, define)
 
         # what colors to use?
         if colors is not None:
@@ -483,10 +504,7 @@ def main(csv_paths, *,
                         else '%s ' % line_chars_[i % len(line_chars_)]
                         if line_chars is not None
                         else '',
-                    ','.join(k_ for i, k_ in enumerate(k)
-                        if k_
-                        if not (i == len(k)-2 and len(x) == 1)
-                        if not (i == len(k)-1 and len(y) == 1)))
+                    ','.join(k_ for k_ in k if k_))
 
                 if label:
                     legend_.append(label)
@@ -685,7 +703,7 @@ if __name__ == "__main__":
         '-b', '--by',
         type=lambda x: [x.strip() for x in x.split(',')],
         help="Fields to render as separate plots. All other fields will be "
-            "summed. Can rename fields with new_name=old_name.")
+            "summed as needed. Can rename fields with new_name=old_name.")
     parser.add_argument(
         '-x',
         type=lambda x: [x.strip() for x in x.split(',')],
@@ -694,15 +712,14 @@ if __name__ == "__main__":
     parser.add_argument(
         '-y',
         type=lambda x: [x.strip() for x in x.split(',')],
-        required=True,
         help="Fields to use for the y-axis. Can rename fields with "
             "new_name=old_name.")
     parser.add_argument(
         '-D', '--define',
-        type=lambda x: (lambda k, v: (k, set(v.split(','))))(*x.split('=', 1)),
+        type=lambda x: (lambda k,v: (k, set(v.split(','))))(*x.split('=', 1)),
         action='append',
-        help="Only include rows where this field is this value (field=value). "
-            "May include comma-separated options.")
+        help="Only include rows where this field is this value. May include "
+            "comma-separated options.")
     parser.add_argument(
         '--color',
         choices=['never', 'always', 'auto'],