timetk: mutate_by_time – R documentation

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mutate_by_time

Mutate (for Time Series Data)

Description

mutate_by_time() is a time-based variant of the popular dplyr::mutate() function that uses .date_var to specify a date or date-time column and .by to group the calculation by groups like "5 seconds", "week", or "3 months".

Usage

mutate_by_time(
  .data,
  .date_var,
  .by = "day",
  ...,
  .type = c("floor", "ceiling", "round")
)

Arguments

`.data`	A `tbl` object or `data.frame`
`.date_var`	A column containing date or date-time values to summarize. If missing, attempts to auto-detect date column.
`.by`	A time unit to summarise by. Time units are collapsed using `lubridate::floor_date()` or `lubridate::ceiling_date()`. The value can be: `second` `minute` `hour` `day` `week` `month` `bimonth` `quarter` `season` `halfyear` `year` Arbitrary unique English abbreviations as in the `lubridate::period()` constructor are allowed.
`...`	Name-value pairs. The name gives the name of the column in the output. The value can be: A vector of length 1, which will be recycled to the correct length. A vector the same length as the current group (or the whole data frame if ungrouped). `NULL`, to remove the column. A data frame or tibble, to create multiple columns in the output.
`.type`	One of "floor", "ceiling", or "round. Defaults to "floor". See `lubridate::round_date`.

Value

A tibble or data.frame

Examples

# Libraries
library(timetk)
library(dplyr)
library(tidyr)

# First value in each month
m4_daily_first_by_month_tbl <- m4_daily %>%
    group_by(id) %>%
    mutate_by_time(
        .date_var = date,
        .by       = "month", # Setup for monthly aggregation
        # mutate recycles a single value
        first_value_by_month  = first(value)
    )
m4_daily_first_by_month_tbl

# Visualize Time Series vs 1st Value Each Month
m4_daily_first_by_month_tbl %>%
    pivot_longer(value:first_value_by_month) %>%
    plot_time_series(date, value, name,
                     .facet_scale = "free", .facet_ncol = 2,
                     .smooth = FALSE, .interactive = FALSE)

timetk

A Tool Kit for Working with Time Series in R

v2.6.1

GPL (>= 3)

Authors

Matt Dancho [aut, cre], Davis Vaughan [aut]

Initial release