# Box ¶

Title
Box Element
Dependencies
Matplotlib
Backends
Matplotlib
Bokeh
In [1]:
import numpy as np
import holoviews as hv
hv.extension('matplotlib')


A  Box  is an annotation that takes a center x-position, a center y-position and a size:

In [2]:
%%opts Box (linewidth=5 color='red') Image (cmap='gray')
data = np.sin(np.mgrid[0:100,0:100][1]/10.0)
data[np.arange(40, 60), np.arange(20, 40)] = -1
data[np.arange(40, 50), np.arange(70, 80)] = -3
hv.Image(data) * hv.Box(-0.2, 0, 0.25 ) * hv.Box(-0, 0, (0.4,0.9) )

Out[2]:

In addition to these arguments, it supports an optional  aspect ratio  :

By default, the size argument results in a square such as the small square shown above. Alternatively, the size can be given as the tuple  (width, height)  resulting in a rectangle. If you only supply a size value, you can still specify a rectangle by specifying an optional aspect value. In addition, you can also set the orientation (in radians, rotating anticlockwise):

In [3]:
%%opts Box (linewidth=5 color='purple') Image (cmap='gray')
data = np.sin(np.mgrid[0:100,0:100][1]/10.0)
data[np.arange(30, 70), np.arange(30, 70)] = -3
hv.Image(data) * hv.Box(-0, 0, 0.25, aspect=3, orientation=-np.pi/4)

Out[3]: