zucsv

Read CSV files into base R data frames, using the zsv C parser as the backend.

zucsv is deliberately small: two exported functions, no R package dependencies, and a bundled copy of the parser so there is nothing to install and nothing to configure. The division of labour is the whole design — zsv decides where rows and fields begin and end, zucsv decides what they mean in R.

Installation

install.packages("zucsv")

Or the development version:

# install.packages("pak")
pak::pak("pedrobtz/zucsv")

Example

library(zucsv)

path <- tempfile(fileext = ".csv")
writeLines(c(
  "id,name,score,active",
  "1,Ada,9.5,TRUE",
  "2,Linus,8.0,FALSE",
  "3,Grace,,TRUE"
), path)

df <- read_csv(path)
df
#>   id  name score active
#> 1  1   Ada   9.5   TRUE
#> 2  2 Linus   8.0  FALSE
#> 3  3 Grace    NA   TRUE

str(df)
#> 'data.frame':    3 obs. of  4 variables:
#>  $ id    : int  1 2 3
#>  $ name  : chr  "Ada" "Linus" "Grace"
#>  $ score : num  9.5 8 NA
#>  $ active: logi  TRUE FALSE TRUE

Types are inferred over logical, integer, double and character. Give col_types to fix them instead — a value that will not convert is an error rather than a silent NA:

read_csv(path, col_types = "character")
read_csv(path, col_types = c("integer", "character", "double", "logical"))

read_csv(path, col_types = "integer")
#> Error: Cannot parse row 2, column 2 ("name") as integer: "Ada"

Other delimiters need no separate function:

read_csv("data.tsv", delimiter = "\t")
read_csv("data.txt", delimiter = ";")

What it does not do

v0.1 reads local files and nothing else. There is no write_csv(), no URL or connection input, no compressed files, no date parsing, no column selection, no skip/n_max. See section 3 of zucsv-design.md for the full list and the reasoning, and section 27 for what is likely to come next.

Behavior worth knowing

These are decisions, not accidents, and each is pinned by a test:

• Blank lines are skipped wherever they appear. A line of only whitespace or only delimiters is not blank — it is a record of empty cells, and must match the table’s width. In a single-column file write an intentional empty cell as ""; a bare empty line is skipped.
• Every record must have the same width. Short rows are not padded.
• Column names are kept exactly, duplicates and empty strings included. No name repair.
• Text must be valid UTF-8. Invalid bytes or an embedded NUL are an error where they occur, rather than something that fails later somewhere less helpful. A BOM is ignored.
• Nothing is trimmed, so " 42" is character, not a number.

Performance

Faster than utils::read.csv() by 2.5–6.8× across shapes; slower than data.table::fread(), which is multi-threaded and single-pass; comparable to a fully materialised vroom, ahead of it on character-heavy data, wide tables and small files. Numbers and method in bench/RESULTS.md.

Licence

MIT. The bundled zsv sources are MIT, copyright Tai Chi Minh Ralph Eastwood, Matt Wong, Guarnerix Inc dba Liquidaty and the zsv contributors; see inst/COPYRIGHTS and src/vendor/zsv/UPSTREAM.