Normalized plot styles across chapters.

I had a lot of problems with lines being visible, and ended up
using different styles in different places. I found a style that
seems to work everywhere and put the code in book_plots.py.

code/book_plots.py

@@ -0,0 +1,74 @@
+# -*- coding: utf-8 -*-
+"""
+Created on Fri May  2 12:21:40 2014
+
+@author: rlabbe
+"""
+import matplotlib.pyplot as plt
+import numpy as np
+
+def bar_plot(pos, ylim=(0,1), title=None):
+    plt.cla()
+    ax = plt.gca()
+    x = np.arange(len(pos))
+    ax.bar(x, pos, color='#30a2da')
+    if ylim:
+        plt.ylim(ylim)
+    plt.xticks(x+0.4, x)
+    if title is not None:
+        plt.title(title)
+
+
+def plot_measurements(xs, ys=None, c='r', lw=2, label='Measurements', **kwargs):
+    """ Helper function to give a consistant way to display
+    measurements in the book.
+    """
+
+    plt.autoscale(tight=True)
+    '''if ys is not None:
+        plt.scatter(xs, ys, marker=marker, c=c, s=s,
+                    label=label, alpha=alpha)
+        if connect:
+           plt.plot(xs, ys, c=c, lw=1, alpha=alpha)
+    else:
+        plt.scatter(range(len(xs)), xs, marker=marker, c=c, s=s,
+                    label=label, alpha=alpha)
+        if connect:
+           plt.plot(range(len(xs)), xs, lw=1, c=c, alpha=alpha)'''
+
+    if ys is not None:
+        plt.plot(xs, ys, c=c, lw=lw, linestyle='--', label=label, **kwargs)
+    else:
+        plt.plot(xs, c=c, lw=lw, linestyle='--', label=label, **kwargs)
+
+
+
+def plot_residual_limits(Ps):
+    std = np.sqrt(Ps)
+
+    plt.plot(-std, c='k', ls=':', lw=2)
+    plt.plot(std, c='k', ls=':', lw=2)
+    plt.fill_between(range(len(std)), -std, std,
+                 facecolor='#ffff00', alpha=0.3)
+
+
+def plot_track(xs, ys=None, label='Track', c='k', lw=2):
+    if ys is not None:
+        plt.plot(xs, ys, c=c, lw=lw, label=label)
+    else:
+        plt.plot(xs, c=c, lw=lw, label=label)
+
+
+#c='#013afe'
+def plot_filter(xs, ys=None, c='#6d904f', label='Filter', **kwargs):
+    if ys is not None:
+        plt.plot(xs, ys, c=c, label=label, **kwargs)
+    else:
+        plt.plot(xs, c=c, label=label, **kwargs)
+
+
+if __name__ == "__main__":
+    p = [0.2245871, 0.06288015, 0.06109133, 0.0581008, 0.09334062, 0.2245871,
+     0.06288015, 0.06109133, 0.0581008,  0.09334062]*2
+    bar_plot(p)
+    plot_measurements(p)