In jl5000/tidygedcom: Handle GEDCOM Files Using Tidyverse Principles

knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>"
)

Introduction

As you would expect with a genealogical data format, dates form a major part of information contained within it. Within tidyged there are a number of different date types that can be defined, and there is a helper function for each type to ensure it is formatted correctly.

Exact dates

Dates that occur on a specific defined date are defined using the date_exact() function:

library(tidyged)

date_exact(1999, 7, 5)
date_exact(1956, 12, 8)
date_exact(2008, 4, 1)

Calendar dates

Calendar dates are the most common type of date used. They can not only be used to create specific dates like date_exact(), they underpin the other date types described below. They can be created using the date_calendar() function:

date_calendar(year = 1999, month = 4, day = 5)
date_calendar(year = 1999, month = 4)
date_calendar(year = 1999)
date_calendar(month = 4, day = 5)

English dates before 1752 were often given in dual format. This can be achieved using the year_is_dual parameter:

date_calendar(year = 1745, month = 4, day = 5, year_is_dual = TRUE)

Years before the Common Era can be defined using the year_is_bce parameter:

date_calendar(year = 105, year_is_bce = TRUE)

Note that only the Gregorian calendar is currently supported.

Approximate dates

Approximate dates (i.e. those expressing uncertainty) use the qualifiers 'about', 'calculated', or 'estimated' in conjunction with a date_calendar() object:

date_calendar(year = 1999, month = 4, day = 5) |> date_approximated(about = TRUE)
date_calendar(year = 1999, month = 4, day = 5) |> date_approximated(calc = TRUE)
date_calendar(year = 1999, month = 4, day = 5) |> date_approximated(est = TRUE)

Date periods

Date periods can take one or two date_calendar() objects:

date_period(start_date = date_calendar(1956, 7, 26),
            end_date = date_calendar(1956, 9, 15))
date_period(start_date = date_calendar(1956, 7, 26))
date_period(end_date = date_calendar(1956, 9, 15))

Providing only one date gives a semi-infinite period.

Date ranges

Date ranges can be defined using date_range(). Unlike date_period(), they describe when an event occurred rather than a duration.

date_range(start_date = date_calendar(1956, 7, 26),
           end_date = date_calendar(1956, 9, 15))
date_range(start_date = date_calendar(1956, 7, 26))
date_range(end_date = date_calendar(1956, 9, 15))

It's important to note that approximate dates cannot be used in date ranges or date periods. The GEDCOM specification does allow arbitrary "date phrases" enclosed in parentheses, but recommends these are added as notes instead. The tidyged package doesn't allow you to create date phrases (only as notes) but will accept them from imported files.

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jl5000/tidygedcom documentation built on June 22, 2022, 5:16 p.m.