n2mfrow {grDevices} | R Documentation |

## Compute Default `mfrow`

From Number of Plots

### Description

Easy setup for plotting multiple figures (in a rectangular layout) on
one page. This computes a sensible default for
`par(mfrow)`

.

### Usage

```
n2mfrow(nr.plots, asp = 1)
```

### Arguments

`nr.plots` |
integer; the number of plot figures you'll want to draw. |

`asp` |
positive number; the target aspect ratio (columns / rows) in
the output. Was implicitly hardwired to |

### Value

A length-two integer vector `(nr, nc)`

giving the positive number of rows
and columns, fulfilling `nr * nc >= nr.plots`

, and currently, for
`asp = 1`

, `nr >= nc >= 1`

.

### Note

Conceptually, this is a quadratic integer optimization problem, with
inequality constraints `nr >= 1`

, `nc >= 1`

, and
`nr.plots >= nr*nc`

(and possibly `nr >= asp*nc`

),
and *two* objective functions which would have to be combined via a
tuning weight, say `w`

, to, e.g.,
`(nr.plots - nr*nc) + w |nr/nc - asp|`

.

The current algorithm is simple and not trying to solve one of these optimization problems.

### Author(s)

Martin Maechler; suggestion of `asp`

by Michael Chirico.

### See Also

### Examples

```
require(graphics)
n2mfrow(8) # 3 x 3
n <- 5 ; x <- seq(-2, 2, length.out = 51)
## suppose now that 'n' is not known {inside function}
op <- par(mfrow = n2mfrow(n))
for (j in 1:n)
plot(x, x^j, main = substitute(x^ exp, list(exp = j)), type = "l",
col = "blue")
sapply(1:14, n2mfrow)
sapply(1:14, n2mfrow, asp=16/9)
```

*grDevices*version 4.4.0 Index]