Handle one point

pygal/line.py

@@ -21,14 +21,18 @@ class Line(BaseGraph):
         self.series.append(
             Serie(title, values))
 
+    def _label(self, label):
+        return Label(('{:.%d%s}' % (
+            self.precision, self.format)).format(label), label)
+
     def _y_labels(self, ymin, ymax):
         step = (ymax - ymin) / 20.
+        if not step:
+            return [self._label(ymin)]
         label = ymin
         labels = []
-        while label < ymax:
+        while label <= ymax:
-            labels.append(
+            labels.append(self._label(label))
-                Label(('{:.%d%s}' % (
-                    self.precision, self.format)).format(label), label))
             label += step
         return labels
 
@@ -42,7 +46,8 @@ class Line(BaseGraph):
     def draw(self):
         self.validate()
         x_step = len(self.series[0].values)
-        x_pos = [x / float(x_step - 1) for x in range(x_step)]
+        x_pos = [x / float(x_step - 1) for x in range(x_step)
+        ] if x_step != 1 else [0]  # Center if only one value
         vals = [val for serie in self.series for val in serie.values]
         margin = Margin(*(4 * [10]))
         ymin, ymax = min(vals), max(vals)

pygal/test/test_line.py

@@ -1,14 +1,20 @@
 from pygal.line import Line
-from pygal.style import LightStyle
 from math import cos, sin
 
 
 def test_simple_line():
-    line = Line(800, 600, style=LightStyle, precision=2, format='f')
+    line = Line(800, 600, precision=2, format='f')
     rng = range(-30, 30, 5)
     line.add('test1', [cos(x / 10.) for x in rng])
     line.add('test2', [sin(x / 10.) for x in rng])
     line.add('test3', [cos(x / 10.) - sin(x / 10.) for x in rng])
     line.x_labels = map(str, rng)
     line.title = "cos sin and cos - sin"
+    line.render()
+
+
+def test_one_dot():
+    line = Line(800, 600)
+    line.add('one dot', [12])
+    line.x_labels = ['one']
     line._in_browser()

pygal/view.py

@@ -12,7 +12,13 @@ class View(object):
     def __init__(self, width, height, xmin, xmax, ymin, ymax):
         self.width = width
         self.height = height
-        self.box = Box(xmin, ymin, xmax - xmin, ymax - ymin)
+        xrng = (xmax - xmin) or 1
+        yrng = (ymax - ymin) or 1
+        if xrng == 1:
+            xmin -= .5
+        if yrng == 1:
+            ymin -= .5
+        self.box = Box(xmin, ymin, xrng, yrng)
 
     def x(self, x):
         return self.width * (x - self.box.x) / float(self.box.width)
@@ -23,6 +29,4 @@ class View(object):
 
     def __call__(self, xy):
         x, y = xy
-        return (
+        return (self.x(x), self.y(y))
-            self.x(x),
-            self.y(y))