Merge pull request #1540 from ixjlyons/siprefix-without-suffix

Support siPrefix with no suffix in SpinBox

doc/source/functions.rst

@@ -65,6 +65,8 @@ SI Unit Conversion Functions
 
 .. autofunction:: pyqtgraph.siEval
 
+.. autofunction:: pyqtgraph.siParse
+
 
 Image Preparation Functions
 ---------------------------
@@ -100,5 +102,3 @@ Miscellaneous Functions
 .. autofunction:: pyqtgraph.systemInfo
 
 .. autofunction:: pyqtgraph.exit
-
-

examples/SpinBox.py

@@ -31,6 +31,8 @@ spins = [
      pg.SpinBox(value=1.0, suffix='V', siPrefix=True, dec=True, step=0.5, minStep=0.01)),
     ("Float with SI-prefixed units,<br>dec step=1.0, minStep=0.001", 
      pg.SpinBox(value=1.0, suffix='V', siPrefix=True, dec=True, step=1.0, minStep=0.001)),
+    ("Float with SI prefix but no suffix",
+     pg.SpinBox(value=1e9, siPrefix=True)),
     ("Float with custom formatting", 
      pg.SpinBox(value=23.07, format='${value:0.02f}',
                 regex='\$?(?P<number>(-?\d+(\.\d+)?)|(-?\.\d+))$')),

pyqtgraph/functions.py

@@ -122,7 +122,25 @@ def siParse(s, regex=FLOAT_REGEX, suffix=None):
 
     Example::
 
-        siParse('100 μV")  # returns ('100', 'μ', 'V')
+        siParse('100 µV")  # returns ('100', 'µ', 'V')
+
+    Note that in the above example, the µ symbol is the "micro sign" (UTF-8
+    0xC2B5), as opposed to the Greek letter mu (UTF-8 0xCEBC).
+
+    Parameters
+    ----------
+    s : str
+        The string to parse.
+    regex : re.Pattern, optional
+        Compiled regular expression object for parsing. The default is a
+        general-purpose regex for parsing floating point expressions,
+        potentially containing an SI prefix and a suffix.
+    suffix : str, optional
+        Suffix to check for in ``s``. The default (None) indicates there may or
+        may not be a suffix contained in the string and it is returned if
+        found. An empty string ``""`` is handled differently: if the string
+        contains a suffix, it is discarded. This enables interpreting
+        characters following the numerical value as an SI prefix.
     """
     s = asUnicode(s)
     s = s.strip()
@@ -131,9 +149,14 @@ def siParse(s, regex=FLOAT_REGEX, suffix=None):
             raise ValueError("String '%s' does not have the expected suffix '%s'" % (s, suffix))
         s = s[:-len(suffix)] + 'X'  # add a fake suffix so the regex still picks up the si prefix
 
+    # special case: discard any extra characters if suffix is explicitly empty
+    if suffix == "":
+        s += 'X'
+
     m = regex.match(s)
     if m is None:
         raise ValueError('Cannot parse number "%s"' % s)
+
     try:
         sip = m.group('siPrefix')
     except IndexError:

pyqtgraph/tests/test_functions.py

@@ -424,5 +424,29 @@ def test_eq():
     assert not eq(set(range(10)), set(range(9)))
 
 
-if __name__ == '__main__':
-    test_interpolateArray()
+@pytest.mark.parametrize("s,suffix,expected", [
+    # usual cases
+    ("100 uV", "V", ("100", "u", "V")),
+    ("100 µV", "V", ("100", "µ", "V")),
+    ("4.2 nV", None, ("4.2", "n", "V")),
+    ("1.2 m", "m", ("1.2", "", "m")),
+    ("1.2 m", None, ("1.2", "", "m")),
+    ("5.0e9", None, ("5.0e9", "", "")),
+    ("2 units", "units", ("2", "", "units")),
+    # siPrefix with explicit empty suffix
+    ("1.2 m", "", ("1.2", "m", "")),
+    ("5.0e-9 M", "", ("5.0e-9", "M", "")),
+    # weirder cases that should return the reasonable thing
+    ("4.2 nV", "nV", ("4.2", "", "nV")),
+    ("4.2 nV", "", ("4.2", "n", "")),
+    ("1.2 j", "", ("1.2", "", "")),
+    ("1.2 j", None, ("1.2", "", "j")),
+    # expected error cases
+    ("100 uV", "v", ValueError),
+])
+def test_siParse(s, suffix, expected):
+    if isinstance(expected, tuple):
+        assert pg.siParse(s, suffix=suffix) == expected
+    else:
+        with pytest.raises(expected):
+            pg.siParse(s, suffix=suffix)

pyqtgraph/widgets/SpinBox.py

@@ -132,8 +132,10 @@ class SpinBox(QtGui.QAbstractSpinBox):
         siPrefix       (bool) If True, then an SI prefix is automatically prepended
                        to the units and the value is scaled accordingly. For example,
                        if value=0.003 and suffix='V', then the SpinBox will display
-                       "300 mV" (but a call to SpinBox.value will still return 0.003). Default
-                       is False.
+                       "300 mV" (but a call to SpinBox.value will still return 0.003). In case
+                       the value represents a dimensionless quantity that might span many
+                       orders of magnitude, such as a Reynold's number, an SI
+                       prefix is allowed with no suffix. Default is False.
         step           (float) The size of a single step. This is used when clicking the up/
                        down arrows, when rolling the mouse wheel, or when pressing 
                        keyboard arrows while the widget has keyboard focus. Note that
@@ -466,7 +468,7 @@ class SpinBox(QtGui.QAbstractSpinBox):
 
         # format the string 
         val = self.value()
-        if self.opts['siPrefix'] is True and len(self.opts['suffix']) > 0:
+        if self.opts['siPrefix'] is True:
             # SI prefix was requested, so scale the value accordingly
 
             if self.val == 0 and prev is not None:
@@ -545,7 +547,7 @@ class SpinBox(QtGui.QAbstractSpinBox):
             return False
             
         # check suffix
-        if suffix != self.opts['suffix'] or (suffix == '' and siprefix != ''):
+        if suffix != self.opts['suffix']:
             return False
            
         # generate value

pyqtgraph/widgets/tests/test_spinbox.py

@@ -23,6 +23,7 @@ def test_SpinBox_defaults():
     (1.45, '1.45 PSI', dict(int=False, decimals=6, suffix='PSI', siPrefix=True)),
     (1.45e-3, '1.45 mPSI', dict(int=False, decimals=6, suffix='PSI', siPrefix=True)),
     (-2500.3427, '$-2500.34', dict(int=False, format='${value:0.02f}')),
+    (1000, '1 k', dict(siPrefix=True, suffix="")),
 ])
 def test_SpinBox_formatting(value, expected_text, opts):
     sb = pg.SpinBox(**opts)
@@ -35,10 +36,11 @@ def test_SpinBox_formatting(value, expected_text, opts):
 @pytest.mark.parametrize("suffix", ["", "V"])
 def test_SpinBox_gui_set_value(suffix):
     sb = pg.SpinBox(suffix=suffix)
+
     sb.lineEdit().setText('0.1' + suffix)
     sb.editingFinishedEvent()
     assert sb.value() == 0.1
-    if suffix != '':
+
     sb.lineEdit().setText('0.1 m' + suffix)
     sb.editingFinishedEvent()
     assert sb.value() == 0.1e-3