debkeepr integrates non-decimal currencies that use the tripartite system of pounds, shillings, and pence into the methodologies of Digital Humanities and the practices of reproducible research. The package makes it possible for historical non-decimal currencies to behave like decimalized numeric values, while also providing support for values with multiple units whose bases can differ. This is accomplished through the implementation of the deb_lsd and deb_decimal classes, which are based on the infrastructure provided by the vctrs package. debkkeepr simplifies the process of performing arithmetic calculations with non-decimal currencies — such as adding £3 13s. 4d. sterling to £8 15s. 9d. sterling — and also provides a basis for analyzing account books with thousands of transactions recorded in non-decimal currencies. The name of the debkeepr package derives from this latter capability of analyzing historical account books that use double-entry bookkeeping.

Installation

You can install debkeepr from GitHub with remotes:

Please open an issue if you have any questions, comments, or requests.

Historical Background

The debkeepr package uses the nomenclature of l, s, and d to represent pounds, shillings, and pence units in non-decimal currencies. The abbreviations derive from the Latin terms libra, solidus, and denarius. The libra was a Roman measurement of weight, while the solidus and denarius were both Roman coins. The denarius was a silver coin from the era of the Republic, in contrast to the golden solidus that was issued in the Late Empire. As the production of silver coins overtook that of gold by the 8th century, a solidus came to represent 12 silver denarii coins, and 240 denarii were — for a time — made from one libra or pound of silver. The custom of counting coins in dozens (solidi) and scores of dozens (librae) spread throughout the Carolingian Empire and became engrained in much of Europe. However, a variety of currencies or monies of account used other bases for the solidus and denarius units. debkeepr provides a consistent manner for dealing with any set of bases within a tripartite system through the bases attribute of deb_lsd and deb_decimal vectors and the unit attribute of deb_decimal vectors.

Translations of libra, solidus, and denarius units:

  • English: pounds, shillings, pence
  • French: livres, sols or sous, deniers
  • Italian: lire, soldi, denari
  • Flemish: ponden, schellingen, groten
  • Dutch: guilders, stuivers, penningen

Resources

Usage

The deb_lsd and deb_decimal classes are implemented to deal with two interrelated problems inherent in historical currencies. Firstly, historical currencies consist of three separate non-decimal units: pounds, shillings, and pence. Secondly, the bases of the shillings and pence units differed by region, coinage, and era. The deb_lsd class maintains the tripartite structure of non-decimal currencies and provides a bases attribute to record the bases for the shillings and pence units. The print methods for both classes show the bases attribute, and deb_decimal vectors include the unit.

Note that all of the functions in debkeepr begin with the prefix deb_, which is short for double-entry bookkeeping.

Both classes allow the user to define the solidus and denarius units of the values, enabling integration of currencies that do not use the standardized bases of 20 shillings to the pound and 12 pence to the shilling. An example of non-standard money of account is the Polish florin found in Dafforne’s practice journal in which a florin consisted of 30 gros of 18 denars. All arithmetic calculations with deb_lsd vectors — sum(), round(), +, -, etc. — normalize the values according to the chosen bases, making it much easier to do the compound unit arithmetic that non-decimal currencies make necessary.

The deb_decimal class represents non-decimal currencies in decimalized form. The class tracks the solidus and denarius bases and the unit represented by the decimalized values through the bases and unit attributes. When working with decimalized data is preferable, the deb_decimal class makes casting from and to deb_lsd possible without losing any metadata about the bases used, and therefore the actual value being represented.

Differences between deb_lsd and deb_decimal vectors

See the Getting Started with debkeepr vignette for an in depth discussion of the similarities and differences between the two classes.

  • The deb_lsd class has the advantage of maintaining the structure and values used by non-decimal currencies, making it easier to identify and present such values.
  • deb_decimal implements a wider array of mathematical functions and arithmetic operations than deb_lsd.
  • Until dplyr integrates record-style vectors based on the vctrs package more fully — which should happen with version 0.9.0 — deb_lsd vectors do not work with the dplyr functions mutate(), summarise(), and arrange(). However, the full complement of dplyr functions work with deb_decimal vectors.
  • ggplot2 does not know how to pick a scale for deb_lsd vectors. In contrast, deb_decimal vectors work properly with ggplot2, though explicitly identifying the scale as continuous — with scale_y_continuous() or scale_x_continuous() — is needed to avoid the appearance of a message.
  • Casting methods between the two classes with deb_as_lsd() and deb_as_decimal() make it possible to move between the two classes without losing any data.
  • deb_lsd and deb_decimal vectors cannot be combined in a single function if they have different bases. The only way to transform the bases of deb_lsd and deb_decimal vectors is explicitly with deb_convert_bases().