Merge pull request #25 from ppinard/angular

Fix issue #19

.travis.yml

@@ -1,17 +1,14 @@
 sudo: false
 language: python
+dist: xenial
 cache:
-  directories:
-  - $HOME/.pip-cache/
+  pip: true
 python:
-  - "2.7"
-  - "3.4"
-  - "3.5"
   - "3.6"
-  - "3.7-dev"
+  - "3.7"
 install:
-- pip install --cache-dir $HOME/.pip-cache --upgrade pip codecov
-- pip install --cache-dir $HOME/.pip-cache --upgrade -r requirements.txt
+- pip install --upgrade pip codecov
+- pip install --upgrade -r requirements.txt
 - python setup.py develop
 script:
 - nosetests

README.rst

@@ -6,7 +6,7 @@ matplotlib-scalebar
 
 .. image:: https://badge.fury.io/py/matplotlib-scalebar.svg
    :target: http://badge.fury.io/py/matplotlib-scalebar
-   
+
 Provides a new artist for matplotlib to display a scale bar, aka micron bar.
 It is particularly useful when displaying calibrated images plotted using
 plt.imshow(...).
@@ -34,15 +34,15 @@ How to use
 There are two modes of operation:
 
 1. Length, value and units of the scale bar are automatically
-   determined based on the specified pixel size *dx* and 
-   *length_fraction*. 
+   determined based on the specified pixel size *dx* and
+   *length_fraction*.
    The value will only take the following numbers:
    1, 2, 5, 10, 15, 20, 25, 50, 75, 100, 125, 150, 200, 500 or 750.
-     
-2. The desired value and units are specified by the user 
+
+2. The desired value and units are specified by the user
    (*fixed_value* and *fixed_units*) and the length is calculated
    based on the specified pixel size *dx*.
-     
+
 The constructor arguments *dx* and *units* specify the pixel dimension.
 For example ``scalebar = ScaleBar(0.2, 'um')`` indicates that each pixel is
 equal to 0.2 micrometer.
@@ -98,6 +98,7 @@ Here are parameters of the **ScaleBar** class constructor.
   * ``imperial-length``: scale bar showing in, ft, yd, mi, etc.
   * ``si-length-reciprocal``: scale bar showing 1/m, 1/cm, etc.
   * ``pixel-length``: scale bar showing px, kpx, Mpx, etc.
+  * ``angle``: scale bar showing °, ʹ (minute of arc) or ʹʹ (second of arc).
   * a ``matplotlib_scalebar.dimension._Dimension`` object
 
 * ``label``: optional label associated with the scale bar
@@ -131,7 +132,7 @@ Here are parameters of the **ScaleBar** class constructor.
 * ``label_formatter``: custom function called to format the scalebar text.
   Needs to take 2 arguments - the scale value and the unit.
   (default: ``None`` which results in ``<value> <unit>``)
-* ``fixed_value``: value for the scale bar. If ``None``, the value is 
+* ``fixed_value``: value for the scale bar. If ``None``, the value is
   automatically determined based on *length_fraction*.
 * ``fixed_units``: units of the *fixed_value*. If ``None`` and
   *fixed_value* is not ``None``, the units of *dx* are used.
@@ -190,14 +191,14 @@ Contributors
 ------------
 
 `@maweigert <https://github.com/maweigert>`_,
-`@crosbyla <https://github.com/crosbyla>`_, 
-`@joschkazj <https://github.com/joschkazj>`_, 
+`@crosbyla <https://github.com/crosbyla>`_,
+`@joschkazj <https://github.com/joschkazj>`_,
 `@AKuederle <https://github.com/AKuederle>`_,
 `@habi <https://github.com/habi>`_,
 `@huangziwei <https://github.com/huangziwei>`_,
 `@SirJohnFranklin <https://github.com/SirJohnFranklin>`_,
 `@alexandrejaguar <https://github.com/alexandrejaguar>`_,
-`@parishcm <https://github.com/parishcm>`_ and 
+`@parishcm <https://github.com/parishcm>`_ and
 `@wiai <https://github.com/wiai>`_
 
 License

doc/example_angular.py

@@ -0,0 +1,23 @@
+import numpy as np
+import matplotlib.pyplot as plt
+import matplotlib.cbook as cbook
+from matplotlib_scalebar.scalebar import ScaleBar, ANGULAR
+
+delta = 0.025
+x = y = np.arange(-3.0, 3.0, delta)
+X, Y = np.meshgrid(x, y)
+Z1 = np.exp(-X ** 2 - Y ** 2)
+Z2 = np.exp(-(X - 1) ** 2 - (Y - 1) ** 2)
+Z = (Z1 - Z2) * 2
+
+fig, axes = plt.subplots(1, 3, figsize=(9, 3))
+
+for ax, dx in zip(axes, [delta, delta / 60, delta / 3600]):
+    ax.imshow(Z)
+
+    scalebar = ScaleBar(dx, "deg", ANGULAR)
+    ax.add_artist(scalebar)
+
+    ax.set_title('dx = {:.6f}deg'.format(dx))
+
+fig.savefig("example_angular.png")

matplotlib_scalebar/dimension.py

@@ -22,20 +22,21 @@ class _Dimension(object):
     def __init__(self, base_units, latexrepr=None):
         self._base_units = base_units
         self._units = {base_units: 1.0}
+
         if latexrepr is None:
             latexrepr = base_units
         self._latexrepr = {base_units: latexrepr}
 
     def add_units(self, units, factor, latexrepr=None):
         """
         Add new possible units.
-        
+
         :arg units: units
         :type units: :class:`str`
-        
-        :arg factor: multiplication factor to convert new units into base units 
+
+        :arg factor: multiplication factor to convert new units into base units
         :type factor: :class:`float`
-        
+
         :arg latexrepr: LaTeX representation of units (if ``None``, use *units)
         :type latexrepr: :class:`str`
         """
@@ -79,14 +80,17 @@ def to_latex(self, units):
             raise ValueError('Unknown units: %s' % units)
         return self._latexrepr[units]
 
+    def create_label(self, value, latexrepr):
+        return '{} {}'.format(value, latexrepr)
+
     @property
     def base_units(self):
         return self._base_units
 
 class SILengthDimension(_Dimension):
 
     def __init__(self):
-        super(SILengthDimension, self).__init__('m')
+        super().__init__('m')
         for prefix, factor in _PREFIXES_FACTORS.items():
             latexrepr = None
             if prefix == u'\u00b5' or prefix == 'u':
@@ -96,7 +100,7 @@ def __init__(self):
 class SILengthReciprocalDimension(_Dimension):
 
     def __init__(self):
-        super(SILengthReciprocalDimension, self).__init__('1/m', 'm$^{-1}$')
+        super().__init__('1/m', 'm$^{-1}$')
         for prefix, factor in _PREFIXES_FACTORS.items():
             latexrepr = '{0}m$^{{-1}}$'.format(prefix)
             if prefix == u'\u00b5' or prefix == 'u':
@@ -106,7 +110,7 @@ def __init__(self):
 class ImperialLengthDimension(_Dimension):
 
     def __init__(self):
-        super(ImperialLengthDimension, self).__init__('ft')
+        super().__init__('ft')
         self.add_units('th', 1 / 12000)
         self.add_units('in', 1 / 12)
         self.add_units('yd', 3)
@@ -118,8 +122,19 @@ def __init__(self):
 class PixelLengthDimension(_Dimension):
 
     def __init__(self):
-        super(PixelLengthDimension, self).__init__('px')
+        super().__init__('px')
         for prefix, factor in _PREFIXES_FACTORS.items():
             if factor < 1:
                 continue
             self.add_units(prefix + 'px', factor)
+
+class AngleDimension(_Dimension):
+
+    def __init__(self):
+        super().__init__('deg', '$^\\circ$')
+        self.add_units("'", 1 / 60, '$^\\prime$')
+        self.add_units("''", 1 / 3600, '$^{\\prime\\prime}$')
+
+    def create_label(self, value, latexrepr):
+        # Overriden to remove space between value and units.
+        return '{}{}'.format(value, latexrepr)