# predict_edges

##### Predict edges based on a hierarchical random graph model

`predict_edges`

uses a hierarchical random graph model to predict
missing edges from a network. This is done by sampling hierarchical models
around the optimum model, proportionally to their likelihood. The MCMC
sampling is stated from `hrg`

, if it is given and the `start`

argument is set to `TRUE`

. Otherwise a HRG is fitted to the graph
first.

##### Usage

```
predict_edges(graph, hrg = NULL, start = FALSE, num.samples = 10000,
num.bins = 25)
```

##### Arguments

- graph
The graph to fit the model to. Edge directions are ignored in directed graphs.

- hrg
A hierarchical random graph model, in the form of an

`igraphHRG`

object.`predict_edges`

s allow this to be`NULL`

as well, then a HRG is fitted to the graph first, from a random starting point.- start
Logical, whether to start the fitting/sampling from the supplied

`igraphHRG`

object, or from a random starting point.- num.samples
Number of samples to use for consensus generation or missing edge prediction.

- num.bins
Number of bins for the edge probabilities. Give a higher number for a more accurate prediction.

##### Value

A list with entries:

The predicted edges, in a two-column matrix of vertex ids.

Probabilities of these edges, according to the fitted model.

The (supplied or fitted) hierarchical random graph model.

##### References

A. Clauset, C. Moore, and M.E.J. Newman. Hierarchical structure
and the prediction of missing links in networks. *Nature* 453, 98--101
(2008);

A. Clauset, C. Moore, and M.E.J. Newman. Structural Inference of Hierarchies
in Networks. In E. M. Airoldi et al. (Eds.): ICML 2006 Ws, *Lecture
Notes in Computer Science* 4503, 1--13. Springer-Verlag, Berlin Heidelberg
(2007).

##### See Also

Other hierarchical random graph functions: `consensus_tree`

,
`hrg.consensus`

; `fit_hrg`

,
`hrg.fit`

; `hrg-methods`

;
`hrg.game`

, `sample_hrg`

;
`hrg_tree`

; `hrg`

,
`hrg.create`

;
`print.igraphHRGConsensus`

;
`print.igraphHRG`

##### Examples

```
# NOT RUN {
## We are not running these examples any more, because they
## take a long time (~15 seconds) to run and this is against the CRAN
## repository policy. Copy and paste them by hand to your R prompt if
## you want to run them.
# }
# NOT RUN {
## A graph with two dense groups
g <- sample_gnp(10, p=1/2) + sample_gnp(10, p=1/2)
hrg <- fit_hrg(g)
hrg
## The consensus tree for it
consensus_tree(g, hrg=hrg, start=TRUE)
## Prediction of missing edges
g2 <- make_full_graph(4) + (make_full_graph(4) - path(1,2))
predict_edges(g2)
# }
```

*Documentation reproduced from package igraph, version 1.0.1, License: GPL (>= 2)*