hatize_byname: Creates a diagonal "hat" matrix from a vector

In MatthewHeun/byname: An Implementation of Matrix Mathematics that Respects Row and Column Names

Creates a diagonal "hat" matrix from a vector

Description

A "hat" matrix (or a diagonal matrix) is one in which the only non-zero elements are along on the diagonal. To "hatize" a vector is to place its elements on the diagonal of an otherwise-zero square matrix. v must be a matrix object with at least one of its two dimensions of length 1 (i.e., a vector). The names on both dimensions of the hatized matrix are the same and taken from the dimension of v that is not 1. Note that the row names and column names are sorted prior to forming the "hat" matrix.

Usage

hatize_byname(v, keep = NULL)

Arguments

v	The vector from which a "hat" matrix is to be created.
keep	One of "rownames" or "colnames" or NULL. If NULL, the default, names are kept from the dimension that is not size 1.

Details

Hatizing a 1x1 vector is potentially undefined. The argument keep determines whether to keep "rownames" or "colnames". By default keep is NULL, meaning that the function should attempt to figure out which dimension's names should be used for the hatized matrix on output. If vector v could ever be 1x1, it is best to set a value for keep when writing code that calls hatize_byname().

If the caller specifies keep = "colnames" when v is a column vector, an error is thrown. If the caller specifies keep = "rownames" when v is a row vector, an error is thrown.

Value

A square "hat" matrix with size equal to the length of v.

Examples

v <- matrix(1:10, ncol = 1, dimnames = list(c(paste0("i", 1:10)), c("c1"))) %>%
  setrowtype("Industries") %>% setcoltype(NA)
v
hatize_byname(v, keep = "rownames")
r <- matrix(1:5, nrow = 1, dimnames = list(c("r1"), c(paste0("c", 1:5)))) %>%
  setrowtype(NA) %>% setcoltype("Commodities")
r
hatize_byname(r, keep = "colnames")
# This also works with lists.
hatize_byname(list(v, v), keep = "rownames")
# A 1x1 column vector is a degenerate case. 
# Row names and rowtype are transferred to the column.
matrix(42, nrow = 1, ncol = 1, dimnames = list("r1")) %>% 
  setrowtype("Product -> Industry") %>% 
  hatize_byname(keep = "rownames")
# A 1x1 row vector is a degenerate case. 
# Column names and coltype are transferred to the row.
matrix(42, nrow = 1, ncol = 1, dimnames = list(NULL, "c1")) %>% 
  setcoltype("Industry -> Product") %>% 
  hatize_byname(keep = "colnames")
# A 1x1 matrix with both row and column names generates a failure.
## Not run: 
matrix(42, nrow = 1, ncol = 1, dimnames = list("r1", "c1")) %>% 
  setrowtype("Product -> Industry") %>% 
  setcoltype("Industry -> Product") %>% 
  hatize_byname()

## End(Not run)
# But you could specify which you want keep, row names or column names.
m <- matrix(42, nrow = 1, ncol = 1, dimnames = list("r1", "c1")) %>% 
  setrowtype("Product -> Industry") %>% 
  setcoltype("Industry -> Product")
m
m %>% 
  hatize_byname(keep = "rownames")
m %>% 
  hatize_byname(keep = "colnames")

MatthewHeun/byname documentation built on Feb. 17, 2024, 4:51 p.m.