# Create a Distance Matrix Between Two Sp Objects

### Description

This function creates a distance matrix between two sp objects (SpatialPointsDataFrame or SpatialPolygonsDataFrame).

### Usage

1 | ```
CreateDistMatrix(knownpts, unknownpts, bypassctrl = FALSE)
``` |

### Arguments

`knownpts` |
sp object; rows of the distance matrix. |

`unknownpts` |
sp object; columns of the distance matrix. |

`bypassctrl` |
logical; bypass the distance matrix size control (see Details). |

### Details

The function returns a full matrix of distances in meters using the
Great Circle distance (WGS84 ellipsoid) method. This is a wrapper
for the `spDists`

function.

.

If the matrix to compute is too large (more than 100,000,000 cells or more than 10,000,000 origins or destinations)
the function sends a confirmation message to warn users about the amount of RAM mobilized.
Use `bypassctrl`

= TRUE to skip this control.

### Value

A distance matrix, row names are `knownpts`

row names, column names are `unknownpts`

row names.

### See Also

CreateGrid

### Examples

1 2 3 4 5 6 7 8 9 10 11 | ```
# Create a SpatialPointsDataFrame grid of spatMask extent and 200 meters
# resolution
data(spatData)
mygrid <- CreateGrid(w = spatMask, resolution = 200)
# Create a distance matrix between known spatPts and mygrid
mymat <- CreateDistMatrix(knownpts = spatPts, unknownpts = mygrid,
bypassctrl = FALSE)
mymat[1:5,1:5]
nrow(spatPts)
nrow(mygrid)
dim(mymat)
``` |