add bokeh sliders.py example

Software/python/sliders.py

@@ -0,0 +1,75 @@
+''' Present an interactive function explorer with slider widgets.
+
+Scrub the sliders to change the properties of the ``sin`` curve, or
+type into the title text box to update the title of the plot.
+
+Use the ``bokeh serve`` command to run the example by executing:
+
+    bokeh serve sliders.py
+
+at your command prompt. Then navigate to the URL
+
+    http://localhost:5006/sliders
+
+in your browser.
+
+'''
+import numpy as np
+
+from bokeh.io import curdoc
+from bokeh.layouts import column, row
+from bokeh.models import ColumnDataSource, Slider, TextInput
+from bokeh.plotting import figure
+
+# Set up data
+N = 200
+x = np.linspace(0, 4*np.pi, N)
+y = np.sin(x)
+source = ColumnDataSource(data=dict(x=x, y=y))
+
+
+# Set up plot
+plot = figure(plot_height=400, plot_width=400, title="my sine wave",
+              tools="crosshair,pan,reset,save,wheel_zoom",
+              x_range=[0, 4*np.pi], y_range=[-2.5, 2.5])
+
+plot.line('x', 'y', source=source, line_width=3, line_alpha=0.6)
+
+
+# Set up widgets
+text = TextInput(title="title", value='my sine wave')
+offset = Slider(title="offset", value=0.0, start=-5.0, end=5.0, step=0.1)
+amplitude = Slider(title="amplitude", value=1.0, start=-5.0, end=5.0, step=0.1)
+phase = Slider(title="phase", value=0.0, start=0.0, end=2*np.pi)
+freq = Slider(title="frequency", value=1.0, start=0.1, end=5.1, step=0.1)
+
+
+# Set up callbacks
+def update_title(attrname, old, new):
+    plot.title.text = text.value
+
+text.on_change('value', update_title)
+
+def update_data(attrname, old, new):
+
+    # Get the current slider values
+    a = amplitude.value
+    b = offset.value
+    w = phase.value
+    k = freq.value
+
+    # Generate the new curve
+    x = np.linspace(0, 4*np.pi, N)
+    y = a*np.sin(k*x + w) + b
+
+    source.data = dict(x=x, y=y)
+
+for w in [offset, amplitude, phase, freq]:
+    w.on_change('value', update_data)
+
+
+# Set up layouts and add to document
+inputs = column(text, offset, amplitude, phase, freq)
+
+curdoc().add_root(row(inputs, plot, width=800))
+curdoc().title = "Sliders"