Fix value formatting

doc/schematics.rst

@@ -1518,24 +1518,13 @@ Label value style
 
 Label values are formatted according to the `label_value_style`
 attribute.  The default is `eng3` which uses an engineering format
-with a maximum of three digits.  Other formats include 'spice' and
-`sci` (scientific).
+with a maximum of three digits.  Other formats include `spice`,
+`sci` (scientific), and `ratfun` (rational functions).
 
-Here's an example with `label_value_style=sci2`:
-
-.. image:: examples/schematics/VRLC1-sci2.png
-   :width: 7cm
-
-Here's an example with `label_value_style=eng`:
-
-.. image:: examples/schematics/VRLC1-eng.png
-   :width: 7cm
-
-Here's an example with `label_value_style=spice`:
-
-.. image:: examples/schematics/VRLC1-spice.png
-   :width: 7cm
+Here's an example showing the different formats:
 
+.. image:: examples/schematics/label_value_style.png
+   :width: 12cm
 
 
 .. _label_placement:

lcapy/labelmaker.py

@@ -13,6 +13,13 @@ def _format_expr(self, expr):
 
     def _format_value_units(self, value, units, style):
 
+        expr = Expr(value, cache=False)
+        if not expr.is_constant or units == '':
+            return expr.latex_math()
+
+        if style == 'ratfun':
+            value = expr
+
         return value_formatter(style=style).latex_math(value, units)
 
     def _format_name(self, cpt_type, cpt_id):
@@ -31,7 +38,7 @@ def _format_name(self, cpt_type, cpt_id):
             name = name + '_{%s}' % subscript
         return latex_format_label('$' + name + '$')
 
-    def make(self, cpt, label_ports=False, style='SI'):
+    def make(self, cpt, label_ports=False, style='eng'):
 
         # There are two possible labels for a component:
         # 1. Component name, e.g., R1
@@ -76,19 +83,13 @@ def make(self, cpt, label_ports=False, style='SI'):
                 expr = cpt.args[1]
                 value_label = self._format_expr(expr)
             elif cpt.classname not in ('TP',):
-                try:
-                    # Handle things like 9/1000 that can occur
-                    # when substituting cpt values.
-                    value = float(sym.Rational(expr))
-                    if cpt.type in units_map:
-                        value_label = self._format_value_units(
-                            value, units_map[cpt.type], style)
-                    else:
-                        value_label = self._format_expr(expr)
-
-                except (ValueError, TypeError):
-                    # This catches non numeric arg.
-                    value_label = self._format_expr(expr)
+
+                if cpt.type in units_map:
+                    units = units_map[cpt.type]
+                else:
+                    units = ''
+
+                value_label = self._format_value_units(expr, units, style)
 
             # Ensure labels are the same when the value is not specified.
             # This will prevent printing the name and value.

lcapy/schematic.py

@@ -552,7 +552,8 @@ def draw(self, filename=None, **kwargs):
         kwargs include:
            'label_ids': True to show component ids
            'label_values': True to display component values
-           'label_value_style': 'eng3' for SI; 'spice3' for SPICE
+           "label_value_style': 'eng' for engineering (SI); 'sci' for scientific;
+                                'ratfun' for rational function; 'spice' for SPICE"
            'label_delimiter': Delimiter between component name and value
            'label_flip': Place label on other side of component
            'annotate_values': True to display component values as separate label

lcapy/valueformatter.py

@@ -8,18 +8,26 @@
 
 class ValueFormatter(object):
 
-    def __init__(self, trim=True, hundreds=False, num_digits=3):
+    def __init__(self, trim=True, hundreds=False, fmt=''):
         """If `hundreds` True format like 100 pF rather than 0.1 nF"""
 
         self.trim = trim
         self.hundreds = hundreds
-        self.num_digits = num_digits
+
+        if fmt == '':
+            self.num_digits = 3
+        else:
+            try:
+                self.num_digits = int(fmt)
+            except ValueError:
+                raise ValueError('Expected a digit for format, got ' + fmt)
 
     def _do(self, value, unit, aslatex):
 
         prefixes = ('f', 'p', 'n', 'u', 'm', '', 'k', 'M', 'G', 'T')
 
-        value = value
+        value = float(value)
+
         if value == 0:
             return self._fmt('0', unit, '', aslatex)
 
@@ -29,12 +37,19 @@ def _do(self, value, unit, aslatex):
             if not self.hundreds:
                 m += 1
             n = int(floor(m / 3))
-            k = int(floor(m)) - n * 3
         else:
             n = 0
-            k = m - 1
 
-        dp = self.num_digits - k
+        # value       m   n
+        # 3141592   6.5   2
+        # 314159.   5.5   1
+        # 31415.9   4.5   1
+        # 3141.59   3.5   1
+        # 314.159   2.5   0
+        # 31.4159   1.5   0
+        # 3.14159   0.5   0
+        # .314159  -0.5   0
+        # .0314159 -1.5  -1
 
         idx = n + 5
         # Handle extremely large or small values without a prefix
@@ -43,13 +58,13 @@ def _do(self, value, unit, aslatex):
         elif idx >= len(prefixes):
             return self._fmt('%e' % value, unit, '', aslatex)
 
-        if dp < 0:
-            dp = 0
-        fmt = '%%.%df' % dp
+        svalue = value * 10**(-3 * n)
 
-        value = value * 10**(-3 * n)
+        # Round to num_digits
+        scale = 10 ** (self.num_digits - 1 - floor(log10(abs(svalue))))
+        rvalue = round(svalue * scale) / scale
 
-        valstr = fmt % value
+        valstr = str(rvalue)
 
         if self.trim:
             # Remove trailing zeroes after decimal point
@@ -129,6 +144,8 @@ class SciValueFormatter(ValueFormatter):
 
     def _do(self, value, unit, aslatex):
 
+        value = float(value)
+
         fmt = '%%.%dE' % (self.num_digits - 1)
 
         valstr = fmt % value
@@ -156,23 +173,30 @@ def _do(self, value, unit, aslatex):
         return valstr + '\\,' + '\\mathrm{' + unit + '}'
 
 
+class RatfunValueFormatter(ValueFormatter):
+
+    def _do(self, value, unit, aslatex):
+
+        if not aslatex:
+            return str(value) + ' ' + unit
+
+        if unit.startswith('$'):
+            return value.latex() + '\\,' + unit[1:-1]
+
+        return value.latex() + '\\,' + '\\mathrm{' + unit + '}'
+
+
 def value_formatter(style='eng3'):
 
     style = style.lower()
 
-    # Split into style and num
-    num = 3
-    for m in range(len(style)):
-        if style[m].isdigit():
-            num = int(style[m:])
-            style = style[0:m]
-            break
-
-    if style == 'eng':
-        return EngValueFormatter(num_digits=num)
-    elif style == 'spice':
-        return SPICEValueFormatter(num_digits=num)
-    elif style == 'sci':
-        return SciValueFormatter(num_digits=num)
+    if style.startswith('eng'):
+        return EngValueFormatter(fmt=style[3:])
+    elif style.startswith('spice'):
+        return SPICEValueFormatter(fmt=style[5:])
+    elif style.startswith('sci'):
+        return SciValueFormatter(fmt=style[3:])
+    elif style.startswith('ratfun'):
+        return RatfunValueFormatter(fmt='')
     else:
         raise ValueError('Unknown style: ' + style)