Question

well I am not looking for how to draw items on 2d Graph, Its just a pictorial representation of what the expected output need to be

I have a list like

a=[]
b=['c','d','e']
c=['a','b','d']
d=['a']
e=['b','a']
l=['g','r','p']
g=['r']
r=['g']
p=['l']

now from above it is clear that b is pointing to c , d ,e

a,b,c,d are closely linked , while the l,g,r,p are linked

can any one tell me an algo ( keeping 2d Picture in mind) how these similar items can be reprsented together.

Above is just an example.
The list will be dynamically created

Answer 1

Have you come across Graphviz? It has algorithms for various different forms of graph layout which I imagine would do a nice job of laying out your small example above. It also includes some simple GUIs to allow you to experiment with the different layouts it supports.

Edit: in response to some clarifications:

If you need to find dense subgraphs within your graph, even if it is fully connected, then you are looking for algorithms that find communities in networks. An example of a recently-developed algorithm doing such on large graphs (2 million+ nodes, representing a social network) efficiently can be found in this paper.