# problem with list: how to count different elements?

Hello experts!

Im working with graphs.

My code is:

```
import numpy as np
import networkx as nx
M = np.zeros([6,6])
M[0,2]=1
M[2,0]=1
M[2,3]=1
M[3,2]=1
M[2,1]=1
M[1,2]=1
M[4,5]=1
M[5,4]=1
G=nx.Graph(M)
A=nx.node_connected_component(G,2)
```

Doing that, `A`

is a list with all the nodes connected with the node `2`

, ie: `A=[0, 1, 2, 3, 2]`

1) Why the element '2' is repeated?
2) If, instead, we use `A=nx.node_connected_component(G,0)`

, we get `A=[0, 1, 2, 3]`

. In this case: why now the element '0' is not repeated?
3) If we have a list `K=[1,2,3,4,1,1,1]`

, and we do `P=list(set(K))`

, we get `P=[1,2,3,4]`

(doing that we can eliminate the repeated elements in the list). But if I do the same with the list `A`

obtained in my code, I get `A=[0, 1, 2, 3, 2]`

. Why this doest work?

Please help!

Thanks a lot