How can I set up a keyboard shortcut for switching input source? I have to change my language option very often. It is hard when I write something with combination of both "English" &amp; "Bangla", because I have to change that option rapidly.

Is there any way to set a keyboard shortcut, so that I can change my language option by it while typing?

I am using MacBook Pro with OS X. 

Here is a screen shot:



Screen Shot of my Preference:
Go to System Preferences → Keyboard → Shortcuts → Input Sources and define a keyboard shortcut there. As you only have two sources, set a single shortcut for one of the options, then pressing the shortcut will toggle the input sources.