metrics: Colormap on arrow-graphs use direction (instead of Y-sign).

wltp/plots.py

@@ -14,6 +14,7 @@
 from numpy import polyfit, polyval
 from wltp import model
 
+import math
 import numpy as np
 
 
@@ -29,7 +30,7 @@ class MidPointNorm(Normalize):
         imshow(X, norm=norm)
     """
     def __init__(self, midpoint=0, vmin=None, vmax=None, clip=False):
-        Normalize.__init__(self,vmin, vmax, clip)
+        Normalize.__init__(self, vmin, vmax, clip)
         self.midpoint = midpoint
 
     def __call__(self, value, clip=None):
@@ -42,11 +43,11 @@ def __call__(self, value, clip=None):
         vmin, vmax, midpoint = self.vmin, self.vmax, self.midpoint
 
         if not (vmin < midpoint < vmax):
-            raise ValueError("midpoint must be between maxvalue and minvalue.")
+            raise ValueError("Midpoint(%s) must be between minvalue(%s) and maxvalue(%s)!"%(midpoint, vmin, vmax))
         elif vmin == vmax:
             result.fill(0) # Or should it be all masked? Or 0.5?
         elif vmin > vmax:
-            raise ValueError("maxvalue must be bigger than minvalue")
+            raise ValueError("Maxvalue(%s) must be bigger than minvalue(%s)!"%(vmin, vmax))
         else:
             vmin = float(vmin)
             vmax = float(vmax)
@@ -139,15 +140,21 @@ def plot_class_limits(axis, y):
 #                bbox=bbox, size=8)
 
 
-def calc_2D_diff_on_Y(X1, Y1, X2, Y2):
+## From http://stackoverflow.com/questions/20924085/python-conversion-between-coordinates
+#
+def cart2pol(x, y):
+    rho = np.sqrt(x**2 + y**2)
+    phi = np.arctan2(y, x)
+    return(rho, phi)
+
+def cartesians_to_polarDiffs(X1, Y1, X2, Y2):
     """
-    Given 2 sets of 2D-points calcs the euclidean distance from 2nd to 1st with sign based on the Y axis.
+    Given 2 sets of 2D-points calcs the polar euclidean-distance  and angle from 2nd-pair of points to 1st-pair.
     """
     U = X2 - X1
     V = Y2 - Y1
-    DIFF = np.sqrt(U ** 2 + V ** 2)
-    DIFF[V < 0] = -DIFF[V < 0]
-    return U, V, DIFF
+    DIFF, ANGLE = cart2pol(U, V)
+    return U, V, DIFF, ANGLE
 
 
 #############
@@ -161,7 +168,7 @@ def plot_xy_diffs_scatter(X, Y, X_REF, Y_REF, ref_label, data_label, diff_label=
     color_diff = 'r'
     alpha = 0.8
 
-    _, _, DIFF = calc_2D_diff_on_Y(X_REF, Y_REF, X, Y)
+    _, _, DIFF, _ = cartesians_to_polarDiffs(X_REF, Y_REF, X, Y)
     if axes_tuple:
         (axes, twin_axis) = axes_tuple
     else:
@@ -204,23 +211,22 @@ def plot_xy_diffs_scatter(X, Y, X_REF, Y_REF, ref_label, data_label, diff_label=
 
 def plot_xy_diffs_arrows(X, Y, X_REF, Y_REF, data_label, ref_label=None,
             data_fmt="+k", data_kws={},
-            diff_label=None, diff_fmt="-r", diff_cmap=cm.PiYG, diff_kws={}, #@UndefinedVariable
+            diff_label=None, diff_fmt="-r", diff_cmap=cm.hsv, diff_kws={}, #@UndefinedVariable cm.PiYG
             title=None, x_label=None, y_label=None, 
             axes_tuple=None,
             mark_sections=None):
     color_diff = 'r'
     alpha = 0.9
     cm_norm = MidPointNorm()
 
-    U, V, DIFF = calc_2D_diff_on_Y(X_REF, Y_REF, X, Y)
+    U, V, DIFF, ANGLE = cartesians_to_polarDiffs(X_REF, Y_REF, X, Y)
 
     if axes_tuple:
-        (axes, twin_axis, cbar_axes) = axes_tuple
+        (axes, twin_axis) = axes_tuple
     else:
         bottom = 0.1
         height = 0.8
         axes = plt.axes([0.1, bottom, 0.80, height])
-        cbar_axes = plt.axes([0.90, bottom, 0.12, height])
 
         ## Prepare axes
         #
@@ -235,7 +241,7 @@ def plot_xy_diffs_arrows(X, Y, X_REF, Y_REF, data_label, ref_label=None,
         twin_axis.yaxis.grid(True, color=color_diff)
 
         plt.title(title, axes=axes)
-        axes_tuple = (axes, twin_axis, cbar_axes)
+        axes_tuple = (axes, twin_axis)
 
 
     if mark_sections == 'classes':
@@ -246,7 +252,7 @@ def plot_xy_diffs_arrows(X, Y, X_REF, Y_REF, data_label, ref_label=None,
     ## Plot data
     #
     l_ref = axes.quiver(X, Y, U, V,
-        DIFF, cmap=diff_cmap, norm=cm_norm,
+        ANGLE, cmap=diff_cmap, norm=cm_norm,
         scale_units='xy', angles='xy', scale=1, 
         width=0.004, alpha=alpha,
         pivot='tip'
@@ -255,29 +261,11 @@ def plot_xy_diffs_arrows(X, Y, X_REF, Y_REF, data_label, ref_label=None,
     l_data, = axes.plot(X, Y, data_fmt, label=data_label, **data_kws)
     l_data.set_picker(3)
 
-    l_diff = twin_axis.plot(X, DIFF, '.', color=color_diff, markersize=0.7)
-    line_points, regress_poly = fit_straight_line(X, DIFF)
+    l_diff = twin_axis.plot(X, V, '.', color=color_diff, markersize=0.7)
+    line_points, regress_poly = fit_straight_line(X, V)
     l_diff_fitted, = twin_axis.plot(line_points, polyval(regress_poly, line_points), diff_fmt, 
         label=diff_label, **diff_kws)
 
-    ## Colormap legend
-    #
-    min_DIFF = DIFF.min()
-    max_DIFF = DIFF.max()
-    nsamples = 20
-    m = np.linspace(min_DIFF, max_DIFF, nsamples)
-    m.resize((nsamples, 1))
-    extent = max_DIFF - min_DIFF
-    cbar_axes.imshow(m, cmap=diff_cmap, norm=cm_norm, aspect=600/extent, origin="lower",
-        extent=[0, 12, min_DIFF, max_DIFF])
-    cbar_axes.xaxis.set_visible(False)
-    cbar_axes.yaxis.set_ticks_position('left')
-    cbar_axes.tick_params(axis='y', colors=color_diff, direction='inout', pad=0, labelsize=10)
-
-    twin_axis.set_ylim([min_DIFF, max_DIFF])      ## Sync diff axes.
-    ###twin_axis.set_axis_off()                   ## NOTE: Hiding axis, hides grids!
-    twin_axis.yaxis.set_ticklabels([])            ## NOTE: Turn it on, to check axes are indeed synced
-
     return axes_tuple, (l_data, l_ref, l_diff, l_diff_fitted)
 
 ## http://stackoverflow.com/questions/13306519/get-data-from-plot-with-matplotlib