dist {stats} | R Documentation |

This function computes and returns the distance matrix computed by using the specified distance measure to compute the distances between the rows of a data matrix.

dist(x, method = "euclidean", diag = FALSE, upper = FALSE, p = 2) as.dist(m, diag = FALSE, upper = FALSE) ## Default S3 method: as.dist(m, diag = FALSE, upper = FALSE) ## S3 method for class 'dist': print(x, diag = NULL, upper = NULL, digits = getOption("digits"), justify = "none", right = TRUE, ...) ## S3 method for class 'dist': as.matrix(x)

`x` |
a numeric matrix, data frame or `"dist"` object. |

`method` |
the distance measure to be used. This must be one of
`"euclidean"` , `"maximum"` , `"manhattan"` ,
`"canberra"` , `"binary"` or `"minkowski"` .
Any unambiguous substring can be given. |

`diag` |
logical value indicating whether the diagonal of the
distance matrix should be printed by `print.dist` . |

`upper` |
logical value indicating whether the upper triangle of the
distance matrix should be printed by `print.dist` . |

`p` |
The power of the Minkowski distance. |

`m` |
An object with distance information to be converted to a
`"dist"` object. For the default method, a `"dist"`
object, or a matrix (of distances) or an object which can be coerced
to such a matrix using `as.matrix()` . (Only the lower
triangle of the matrix is used, the rest is ignored). |

`digits, justify` |
passed to `format` inside of
`print()` . |

`right, ...` |
further arguments, passed to the (next)
`print` method. |

Available distance measures are (written for two vectors *x* and
*y*):

`euclidean`

:- Usual square distance between the two vectors (2 norm).
`maximum`

:- Maximum distance between two components of
*x*and*y*(supremum norm) `manhattan`

:- Absolute distance between the two vectors (1 norm).
`canberra`

:*sum(|x_i - y_i| / |x_i + y_i|)*. Terms with zero numerator and denominator are omitted from the sum and treated as if the values were missing.`binary`

:- (aka
*asymmetric binary*): The vectors are regarded as binary bits, so non-zero elements are ‘on’ and zero elements are ‘off’. The distance is the*proportion*of bits in which only one is on amongst those in which at least one is on. `minkowski`

:- The
*p*norm, the*p*th root of the sum of the*p*th powers of the differences of the components.

Missing values are allowed, and are excluded from all computations
involving the rows within which they occur.
Further, when `Inf`

values are involved, all pairs of values are
excluded when their contribution to the distance gave `NaN`

or
`NA`

.

If some columns are excluded in calculating a Euclidean, Manhattan,
Canberra or Minkowski distance, the sum is scaled up proportionally
to the number of columns used. If all pairs are excluded when calculating a
particular distance, the value is `NA`

.

The `"dist"`

method of `as.matrix()`

and `as.dist()`

can be used for conversion between objects of class `"dist"`

and conventional distance matrices.

`as.dist()`

is a generic function. Its default method handles
objects inheriting from class `"dist"`

, or coercible to matrices
using `as.matrix()`

. Support for classes representing
distances (also known as dissimilarities) can be added by providing an
`as.matrix()`

or, more directly, an `as.dist`

method
for such a class.

`dist`

returns an object of class `"dist"`

.

The lower triangle of the distance matrix stored by columns in a
vector, say `do`

. If `n`

is the number of
observations, i.e., `n <- attr(do, "Size")`

, then
for *i < j <= n*, the dissimilarity between (row) i and j is
`do[n*(i-1) - i*(i-1)/2 + j-i]`

.
The length of the vector is *n*(n-1)/2*, i.e., of order *n^2*.

The object has the following attributes (besides `"class"`

equal
to `"dist"`

):

`Size` |
integer, the number of observations in the dataset. |

`Labels` |
optionally, contains the labels, if any, of the observations of the dataset. |

`Diag, Upper` |
logicals corresponding to the arguments `diag`
and `upper` above, specifying how the object should be printed. |

`call` |
optionally, the `call` used to create the
object. |

`method` |
optionally, the distance method used; resulting from
`dist()` , the (`match.arg()` ed) `method`
argument. |

Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988)
*The New S Language*.
Wadsworth & Brooks/Cole.

Mardia, K. V., Kent, J. T. and Bibby, J. M. (1979)
*Multivariate Analysis.* Academic Press.

Borg, I. and Groenen, P. (1997)
*Modern Multidimensional Scaling. Theory and Applications.*
Springer.

`daisy`

in the **cluster** package with more
possibilities in the case of *mixed* (continuous / categorical)
variables.
`hclust`

.

x <- matrix(rnorm(100), nrow=5) dist(x) dist(x, diag = TRUE) dist(x, upper = TRUE) m <- as.matrix(dist(x)) d <- as.dist(m) stopifnot(d == dist(x)) ## example of binary and canberra distances. x <- c(0, 0, 1, 1, 1, 1) y <- c(1, 0, 1, 1, 0, 1) dist(rbind(x,y), method="binary") ## answer 0.4 = 2/5 dist(rbind(x,y), method="canberra") ## answer 2 * (6/5) ## Examples involving "Inf" : ## 1) x[6] <- Inf (m2 <- rbind(x,y)) dist(m2, method="binary")# warning, answer 0.5 = 2/4 ## These all give "Inf": stopifnot(Inf == dist(m2, method= "euclidean"), Inf == dist(m2, method= "maximum"), Inf == dist(m2, method= "manhattan")) ## "Inf" is same as very large number: x1 <- x; x1[6] <- 1e100 stopifnot(dist(cbind(x ,y), method="canberra") == print(dist(cbind(x1,y), method="canberra"))) ## 2) y[6] <- Inf #-> 6-th pair is excluded dist(rbind(x,y), method="binary") # warning; 0.5 dist(rbind(x,y), method="canberra") # 3 dist(rbind(x,y), method="maximum") # 1 dist(rbind(x,y), method="manhattan")# 2.4

[Package *stats* version 2.1.0 Index]