Euclid | R Documentation |

Function `Euclid`

carries out the calculation of pairwise Euclidean
distances within a set of coordinates or between two sets thereof, with
optional weights.

```
Euclid(x, y, squared = FALSE)
```

`x` |
A set of coordinates in the form of a |

`y` |
An optional second set of coordinates in the same dimensions as
argument |

`squared` |
Should the squared Euclidean distances be returned (default: FALSE). |

When only one set of coordinates is given to the function (i.e.,
when argument `y`

is omitted), the function returns the pairwise
distances in the form of a 'dist-class' object representing a
lower-triangle matrix. If weights are omitted, the result is identical to
that produced by function dist with argument
`method = "euclidean"`

(the function's default).

The standard 'R' function used to calculate the Euclidean distance
(`dist`

), only allows one to calculate pairwise distances between
the rows of a single matrix of Cartesian coordinates and return a
'dist-class' object, which is a one-dimensional array meant to be
interpreted as a lower-triangular matrix. Function `Euclid`

can also be
provided two data matrices (arguments `x`

and `y`

) and output a
rectangular matrix of the Euclidean distances.

A 'dist-class' object or, whenever `y`

is provided,
a `matrix`

with as many rows as the number of rows in `x`

and as many columns as the number of rows in `y`

.

Guillaume Guenard and Pierre Legendre, Bertrand Pages Maintainer: Guillaume Guenard <guillaume.guenard@gmail.com>

The 'dist-class' and associated methods.

```
## A set of reference points:
x <- cbind(c(1,4,5,2,8,4), c(3,6,7,1,3,2))
dimnames(x) <- list(LETTERS[1:6], c("x", "y"))
## The pairwise Euclidean distances among the reference points:
d1 <- Euclid(x)
d1
## That result is the same as that obtained from function dist:
d2 <- dist(x, method = "euclidean")
all(d1 == d2)
## A second set of points:
y <- cbind(c(3,5,7), c(3,6,8))
dimnames(y) <- list(LETTERS[7:9], c("x", "y"))
## The distances between the points in y (rows) and x (columns):
Euclid(x, y)
```

guenardg/codep documentation built on April 15, 2023, 6:47 a.m.

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