stress majorization for larger graphs based on a set of pivot nodes.

## Usage

```
layout_with_sparse_stress(g, pivots, weights = NA, iter = 500)
layout_igraph_sparse_stress(g, pivots, weights = NA, iter = 500, circular)
```

## Arguments

- g
igraph object

- pivots
number of pivots

- weights
ignored

- iter
number of iterations during stress optimization

- circular
not used

## Details

The layout_igraph_* function should not be used directly. It is only used as an argument for plotting with 'igraph'. 'ggraph' natively supports the layout.

## References

Ortmann, M. and Klimenta, M. and Brandes, U. (2016). A Sparse Stress Model. https://arxiv.org/pdf/1608.08909.pdf

## Examples

```
if (FALSE) {
library(igraph)
library(ggraph)
g <- sample_gnp(1000,0.005)
ggraph(g,layout = "sparse_stress",pivots = 100)+
geom_edge_link0(edge_colour = "grey66")+
geom_node_point(shape = 21,fill = "grey25",size = 5)+
theme_graph()
}
```