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Cut an Event Log into Pathways

Source: R/extract_pathways.R
extract_pathways.Rd

Splits a long event log into pathways and returns them as a tidy data.frame, one row per pathway, ready to tabulate against an outcome or to feed to a sequence model.

Usage

extract_pathways(
  data,
  action,
  group,
  order = NULL,
  type = c("unit", "segments", "anchored"),
  anchor = NULL,
  terminal = NULL,
  resolve = NULL,
  sep = " -> "
)

Arguments

data

A long-format data.frame, one row per event, already in chronological order within each group (or with order supplied).

action

Name of the column holding the state / event label.

group

Character vector of column names defining the unit a pathway may not cross – typically the actor, or actor and session.

order

Optional column giving the within-group event order. When NULL (default) the existing row order is used.

type

The cut to make:

"unit"

(default) one pathway per group. With terminal, the group is truncated at its last terminal state so the pathway ends on an outcome rather than on whatever followed.

"segments"

consecutive, non-overlapping pathways: the group is cut after every terminal state, so each pathway ends on one. Every event belongs to exactly one pathway.

"anchored"

one pathway per occurrence of anchor, closing at the next terminal state. Pathways may overlap and events between a terminal and the next anchor belong to none.

anchor

State that opens a pathway when type = "anchored". Ignored by the other cuts. Default NULL.

terminal

States that close a pathway, the closing state included. Required for "segments" and "anchored"; optional for "unit", where it truncates.

resolve

Optional named list giving a resolution label to append as the pathway's final state. Each element is a character vector of states; a pathway takes the label of the first element whose states all occur in it, so order the list from most specific to least. Pathways matching nothing are labelled "Unresolved". The label becomes the last element of path and the value of closes, and the raw final state is kept in ends.

sep

Separator used when pasting the path. Default " -> ".

Value

A data.frame with one row per pathway: the group columns, pathway (an integer id within group), path (the states pasted with sep), length, opens (first state) and closes (last state). With resolve, closes holds the resolution label instead and a further ends column carries the raw final state. Pathways are returned in the order they occur.

See also

sequence_compare, outcome_model

Examples

log <- data.frame(
  id  = c(1, 1, 1, 1, 1, 1, 2, 2, 2),
  act = c("Try", "Wrong", "Hint", "Retry", "Right", "Praise",
          "Try", "Wrong", "Retry"),
  stringsAsFactors = FALSE
)
# Each failure and its consequence:
extract_pathways(log, action = "act", group = "id", type = "anchored",
                 anchor = "Wrong", terminal = c("Right", "Wrong"))
#>   id pathway                            path length opens closes
#> 1  1       1 Wrong -> Hint -> Retry -> Right      4 Wrong  Right

# Each id as one episode:
extract_pathways(log, action = "act", group = "id")
#>   id pathway                                             path length opens
#> 1  1       1 Try -> Wrong -> Hint -> Retry -> Right -> Praise      6   Try
#> 2  2       1                            Try -> Wrong -> Retry      3   Try
#>   closes
#> 1 Praise
#> 2  Retry