Requesting a shrub Id.:
IISER campus adjoining Agasthyamalai biosphere reserve,Thiruvananthapuram.
A mauve colored flower with papilionaceous corolla. It smells pleasant. 
Found growing in the sides of footpaths.

Please check Fabaceae in FoI and efi.

This is Canavalia, as per images and details herein.

Canavalia ensiformis (L.) DC. ??

Difficult to say without fruits and with these images.