grid {graphics} | R Documentation

## Add Grid to a Plot

### Description

`grid` adds an `nx` by `ny` rectangular grid to an existing plot.

### Usage

    grid(nx = NULL, ny = nx, col = "lightgray", lty = "dotted", lwd = NULL,
         equilogs = TRUE)

### Arguments

`nx,ny` | number of cells of the grid in x and y direction. When `NULL`, as per default, the grid aligns with the tick marks on the corresponding default axis (i.e., tickmarks as computed by `axTicks`). When `NA`, no grid lines are drawn in the corresponding direction.
`col` | character or (integer) numeric; color of the grid lines.
`lty` | character or (integer) numeric; line type of the grid lines.
`lwd` | non-negative numeric giving line width of the grid lines; defaults to `par("lwd")`.
`equilogs` | logical, only used when log coordinates and alignment with the axis tick marks are active. Setting{equilogs = FALSE} in that case gives non equidistant tick aligned grid lines.

### Note

If more fine tuning is required, use `abline(h = ., v = .)` directly.

### See Also

`plot`, `abline`, `lines`, `points`.

### Examples

    plot(1:3)
    grid(NA, 5, lwd = 2) # grid only in y-direction

    data(iris)
    ## maybe change the desired number of tick marks:  par(lab=c(mx,my,7))
    op <- par(mfcol = 1:2)
    with(iris,
         {
         plot(Sepal.Length, Sepal.Width, col = as.integer(Species),
              xlim = c(4, 8), ylim = c(2, 4.5), panel.first = grid(),
              main = "with(iris,  plot(...., panel.first = grid(), ..) )")
         plot(Sepal.Length, Sepal.Width, col = as.integer(Species),
              panel.first = grid(3, lty=1,lwd=2),
              main = "... panel.first = grid(3, lty=1,lwd=2), ..")
         }
        )
    par(op)

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