index function

Tensor Indices

Functions to get or set the names of the dimensions of an array.

index(x)

index(x) <- value

Arguments

• x: array.
• value: vector of indices.

Returns

Vector of indices.

Functions

• index(x) \<- value: set indices.

Examples

### array with no indices
x <- array(1, dim = c(1, 3, 2))
index(x)

### indices on initialization
x <- array(1, dim = c(i=1, j=3, k=2))
index(x)

### set indices on the fly
x <- array(1, dim = c(1, 3, 2))
index(x) <- c("i", "j", "k")
index(x)

References

Guidotti E (2022). "calculus: High-Dimensional Numerical and Symbolic Calculus in R." Journal of Statistical Software, 104(5), 1-37. tools:::Rd_expr_doi("10.18637/jss.v104.i05")

See Also

Other tensor algebra: contraction(), delta(), diagonal(), einstein(), epsilon()