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## [igraph] different result with "sparse" = T or F in get.adjacency

**From**: |
Sylvain Loiseau |

**Subject**: |
[igraph] different result with "sparse" = T or F in get.adjacency |

**Date**: |
Sun, 23 Aug 2009 13:11:31 +0200 |

**User-agent**: |
Opera Mail/9.62 (Linux) |

Hi,

`I was struggling for having sparse adjacency matrix and just found that it
``is implemented in get.adjacency... :-(
`

`But I don't understand while there is a difference between the two
``following adjacency matrix (the first with "sparse=T", the second with
``"sparse=F"), based on a graph with loop :
`
# the graph used

reflexif(clique3k)

Vertices: 3
Edges: 6
Directed: FALSE
Edges:
[0] 'A' -- 'B'
[1] 'B' -- 'C'
[2] 'A' -- 'C'
[3] 'A' -- 'A'
[4] 'B' -- 'B'
[5] 'C' -- 'C'

get.adjacency(reflexif(clique3k), sparse=T)

3 x 3 sparse Matrix of class "dgTMatrix"
A B C
A 2 1 1
B 1 2 1
C 1 1 2

get.adjacency(reflexif(clique3k))

A B C
A 1 1 1
B 1 1 1
C 1 1 1
Best,
Sylvain

**[igraph] different result with "sparse" = T or F in get.adjacency**,
*Sylvain Loiseau* **<=**