Added bokeh subdir and moved notebook into subdir

Added bokeh-server-example.py

applications/data_visualisation/bokeh/bokeh-server-example.py

+# myapp.py
+
+import os
+import os.path as op
+from subprocess import check_output as run
+from tempfile import TemporaryDirectory
+
+import nibabel as nb
+from bokeh.layouts import column
+from bokeh.models import Button
+from bokeh.plotting import figure, curdoc
+
+# load MNI152
+FSLDIR = os.environ['FSLDIR']
+fname = f'{FSLDIR}/data/standard/MNI152_T1_1mm.nii.gz'
+
+d = nb.load(fname).get_fdata()
+d0 = d[:, :, d.shape[2] // 2].squeeze()
+
+# plot center axial slice
+p = figure(x_range=(0, 100), y_range=(0, 100), tooltips=[("x", "$x"), ("y", "$y"), ("value", "@image")])
+p.image(image=[d0.T], x=0, y=0, dw=100, dh=100, palette="Greys256", level="image")
+
+
+# create a callback to run BET and show result
+def callback():
+    with TemporaryDirectory() as tmp:
+        bet_name = op.join(tmp, 'betted_img.nii.gz')
+
+        print('running bet')
+        out = run(f'bet {fname} {bet_name}'.split())
+        print(out)
+
+        d = nb.load(bet_name).get_fdata()
+        d0 = d[:, :, d.shape[2] // 2].squeeze()
+
+        p.image(image=[d0.T], x=0, y=0, dw=100, dh=100, palette="Greys256", level="image")
+
+
+# add a button widget and configure with the call back
+button = Button(label="BET Me")
+button.on_click(callback)
+
+# put the button and plot in a layout and add to the document
+curdoc().add_root(column(button, p))