cast_dim2flat: Cast Dimensional List into a Flattened List

In broadcast: Broadcasted Array Operations Like 'NumPy'

Cast Dimensional List into a Flattened List

Description

cast_dim2flat() casts a dimensional list (i.e. recursive array) into a flat list (i.e. recursive vector), but with names that indicate the original dimensional positions of the elements.

Primary purpose for this function is to facilitate printing or summarizing dimensional lists.

Usage

cast_dim2flat(x, ...)

## Default S3 method:
cast_dim2flat(x, ...)

Arguments

x	a list
...	further arguments passed to or from methods.

Value

A flattened list, with names that indicate the original dimensional positions of the elements.

See Also

broadcast_casting

Examples

# Example 1: Basics ====
x <- list(
  group1 = list(
    class1 = list(
      height = rnorm(10, 170),
      weight = rnorm(10, 80),
      sex = sample(c("M", "F", NA), 10, TRUE)
    ),
    class2 = list(
      height = rnorm(10, 170),
      weight = rnorm(10, 80),
      sex = sample(c("M", "F", NA), 10, TRUE)
    )
  ),
  group2 = list(
    class1 = list(
      height = rnorm(10, 170),
      weight = rnorm(10, 80),
      sex = sample(c("M", "F", NA), 10, TRUE)
    ),
    class2 = list(
      height = rnorm(10, 170),
      weight = rnorm(10, 80),
      sex = sample(c("M", "F", NA), 10, TRUE)
    )
  )
)

# predict what dimensions `x` would have if casted as dimensional:
hier2dim(x)

x2 <- cast_hier2dim(x) # cast as dimensional

# since the original list uses the same names for all elements within the same depth,
# dimnames can be set easily:
dimnames(x2) <- list( # go from deep names to surface names
  c("height", "weight", "sex"),
  c("class1", "class2"),
  c("group1", "group2")
)

print(x2) # very compact, maybe too compact...?

# print a small portion of the list, but less compact:
cast_dim2flat(x2[, 1:2, "group1", drop = FALSE])


# Example 2: Cast from outside to inside ====
x <- list(
  group1 = list(
    class1 = list(
      height = rnorm(10, 170),
      weight = rnorm(10, 80),
      sex = sample(c("M", "F", NA), 10, TRUE)
    ),
    class2 = list(
      height = rnorm(10, 170),
      weight = rnorm(10, 80),
      sex = sample(c("M", "F", NA), 10, TRUE)
    )
  ),
  group2 = list(
    class1 = list(
      height = rnorm(10, 170),
      weight = rnorm(10, 80),
      sex = sample(c("M", "F", NA), 10, TRUE)
    ),
    class2 = list(
      height = rnorm(10, 170),
      weight = rnorm(10, 80),
      sex = sample(c("M", "F", NA), 10, TRUE)
    )
  )
)

# by default, `in2out = TRUE`;
# for this example, `in2out = FALSE` is used

# predict what dimensions `x` would have if casted as dimensional:
hier2dim(x, in2out = FALSE)

x2 <- cast_hier2dim(x, in2out = FALSE) # cast as dimensional

# since the original list uses the same names for all elements within the same depth,
# dimnames can be set easily:
# because in2out = FALSE, go from the shallow names to the deeper names:
dimnames(x2) <- list( # notice the order here is reversed, because in2out = FALSE
  c("group1", "group2"),
  c("class1", "class2"),
  c("height", "weight", "sex")
)

print(x2) # very compact, maybe too compact...?

# print a small portion of the list, but less compact:
cast_dim2flat(x2["group1", 1:2, , drop = FALSE])



# Example 3: padding ====

# For Example 3, take the same list as before, but remove x$group1$class2:

x <- list(
  group1 = list(
    class1 = list(
      height = rnorm(10, 170),
      weight = rnorm(10, 80),
      sex = sample(c("M", "F", NA), 10, TRUE)
    )
  ),
  group2 = list(
    class1 = list(
      height = rnorm(10, 170),
      weight = rnorm(10, 80),
      sex = sample(c("M", "F", NA), 10, TRUE)
    ),
    class2 = list(
      height = rnorm(10, 170),
      weight = rnorm(10, 80),
      sex = sample(c("M", "F", NA), 10, TRUE)
    )
  )
)


hier2dim(x) # as indicated here, dimension 2 (i.e. columns) will have padding

# casting this to a dimensional list will resulting in padding with `NULL`:
x2 <- cast_hier2dim(x)
print(x2)
# The `NULL` values are added for padding.
# This is because all slices of the same dimension need to have the same number of elements.  
# For example, all rows need to have the same number of columns.

# one can also use custom padding:
x2 <- cast_hier2dim(x, padding = list(~ "this is padding"))
print(x2)

dimnames(x2) <- list(
  c("height", "weight", "sex"),
  c("class1", "class2"),
  c("group1", "group2")
)

print(x2)

cast_dim2flat(x2[1:2, , , drop = FALSE])

# we can also use in2out = FALSE:
x2 <- cast_hier2dim(x, in2out = FALSE, padding = list(~ "this is padding"))
dimnames(x2) <- list( # notice the order here is reversed, because in2out = FALSE
  c("group1", "group2"),
  c("class1", "class2"),
  c("height", "weight", "sex")
  
)
print(x2)

cast_dim2flat(x2[, , 1:2, drop = FALSE])

broadcast documentation built on Sept. 15, 2025, 5:08 p.m.