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Squash overlapping intervals into non-overlapping spans

Source: R/squash.R
squash.Rd

phint_squash() and datetime_squash() merge overlapping or adjacent intervals into a minimal set of non-overlapping, non-adjacent time spans.

  • phint_squash() takes a <phinterval> or <Interval> vector

  • datetime_squash() takes separate start and end datetime vectors

When by = NULL (the default), all intervals are merged into a single phinterval element. When by is provided, intervals are grouped and merged separately within each group, creating one phinterval element per unique value of by.

Usage

phint_squash(
  phint,
  by = NULL,
  na.rm = TRUE,
  empty_to = c("hole", "na", "empty"),
  order_by = FALSE,
  keep_by = FALSE
)

datetime_squash(
  start,
  end,
  by = NULL,
  na.rm = TRUE,
  empty_to = c("hole", "na", "empty"),
  order_by = FALSE,
  keep_by = FALSE
)

Arguments

phint

[phinterval / Interval]

A <phinterval> or <Interval> vector.

by

[vector / data.frame / NULL]

An optional grouping vector or data frame. When provided, intervals are grouped by by and merged separately within each group. If NULL (the default), all intervals are merged into a single phinterval element.

For datetime_squash(), by must be recyclable with the recycled length of start and end.

by may be any vector in the vctrs sense. See vctrs::obj_is_vector() for details.

na.rm

[TRUE / FALSE]

Should NA elements be removed before squashing? If FALSE and any NA elements are present, the result for that group is NA. Defaults to TRUE.

empty_to

["hole" / "na" / "empty"]

How to handle empty inputs (length-0 vectors or groups with only NA values when na.rm = TRUE):

  • "hole" (default): Return a hole

  • "na": Return an NA phinterval

  • "empty": Return a length-0 phinterval vector

order_by

[TRUE / FALSE]

Should the output be ordered by the values in by? If FALSE (the default), the output order matches the first appearance of each group in by. If TRUE, the output is sorted by the unique values of by. Only used when by is not NULL.

keep_by

[TRUE / FALSE]

Should the by values be returned alongside the result? If FALSE (the default), returns a <phinterval> vector. If TRUE, returns a tibble::tibble() with columns by and phint. Requires by to be non-NULL.

start

[POSIXct / POSIXlt / Date]

A vector of start times. Must be recyclable with end. Only used in datetime_squash().

end

[POSIXct / POSIXlt / Date]

A vector of end times. Must be recyclable with start. Only used in datetime_squash().

Value

When keep_by = FALSE:

  • If by = NULL: A length-1 <phinterval> vector (or length-0 if the input is empty and empty_to = "empty")

  • If by is provided: A <phinterval> vector with one element per unique value of by

When keep_by = TRUE: A tibble::tibble() with columns by and phint.

Details

These functions are particularly useful in aggregation workflows with dplyr::summarize() to combine intervals within groups.

Examples

jan_1_to_5 <- interval(as.Date("2000-01-01"), as.Date("2000-01-05"))
jan_3_to_9 <- interval(as.Date("2000-01-03"), as.Date("2000-01-09"))
jan_11_to_12 <- interval(as.Date("2000-01-11"), as.Date("2000-01-12"))

# phint_squash: merge intervals from a phinterval/Interval vector
phint_squash(c(jan_1_to_5, jan_3_to_9, jan_11_to_12))
#> <phinterval<UTC>[1]>
#> [1] {2000-01-01--2000-01-09, 2000-01-11--2000-01-12}

# datetime_squash: merge intervals from start/end vectors
datetime_squash(
  start = as.Date(c("2000-01-01", "2000-01-03", "2000-01-11")),
  end = as.Date(c("2000-01-05", "2000-01-09", "2000-01-12"))
)
#> <phinterval<UTC>[1]>
#> [1] {2000-01-01--2000-01-09, 2000-01-11--2000-01-12}

# NA values are removed by default
phint_squash(c(jan_1_to_5, jan_3_to_9, jan_11_to_12, NA))
#> <phinterval<UTC>[1]>
#> [1] {2000-01-01--2000-01-09, 2000-01-11--2000-01-12}

# Set na.rm = FALSE to propagate NA values
phint_squash(c(jan_1_to_5, jan_3_to_9, jan_11_to_12, NA), na.rm = FALSE)
#> <phinterval<UTC>[1]>
#> [1] <NA>

# Squash within groups
phint_squash(
  c(jan_1_to_5, jan_3_to_9, jan_11_to_12),
  by = c(1, 1, 2)
)
#> <phinterval<UTC>[2]>
#> [1] {2000-01-01--2000-01-09} {2000-01-11--2000-01-12}

# Return a data frame with by values
phint_squash(
  c(jan_1_to_5, jan_3_to_9, jan_11_to_12),
  by = c("A", "A", "B"),
  keep_by = TRUE
)
#> # A tibble: 2 × 2
#>   by    phint                   
#>   <chr> <phint<UTC>>            
#> 1 A     {2000-01-01--2000-01-09}
#> 2 B     {2000-01-11--2000-01-12}

# Control output order with order_by
phint_squash(
  c(jan_1_to_5, jan_3_to_9, jan_11_to_12),
  by = c(2, 2, 1),
  order_by = TRUE
)
#> <phinterval<UTC>[2]>
#> [1] {2000-01-11--2000-01-12} {2000-01-01--2000-01-09}

# empty_to determines the result of empty inputs
empty <- phinterval()
phint_squash(empty, empty_to = "hole")
#> <phinterval<UTC>[1]>
#> [1] <hole>
phint_squash(empty, empty_to = "na")
#> <phinterval<UTC>[1]>
#> [1] <NA>
phint_squash(empty, empty_to = "empty")
#> <phinterval<UTC>[0]>