seek: Extract Matching Lines from Files

In seekr: Extract Matching Lines from Matching Files

Extract Matching Lines from Files

Description

These functions search through one or more text files, extract lines matching a regular expression pattern, and return a tibble containing the results.

• seek(): Discovers files inside one or more directories (recursively or not), applies optional file name and text file filtering, and searches lines.

• seek_in(): Searches inside a user-provided character vector of files.

Usage

seek(
  pattern,
  path = ".",
  ...,
  filter = NULL,
  negate = FALSE,
  recurse = FALSE,
  all = FALSE,
  relative_path = TRUE,
  matches = FALSE
)

seek_in(files, pattern, ..., matches = FALSE)

Arguments

pattern	A regular expression pattern used to match lines.
path	A character vector of one or more directories where files should be discovered (only for seek()).
...	Additional arguments passed to readr::read_lines(), such as skip, n_max, or locale.
filter	Optional. A regular expression pattern used to filter file paths before reading. If NULL, all text files are considered.
negate	Logical. If TRUE, files matching the filter pattern are excluded instead of included. Useful to skip files based on name or extension.
recurse	If TRUE recurse fully, if a positive number the number of levels to recurse.
all	If TRUE hidden files are also returned.
relative_path	Logical. If TRUE, file paths are made relative to the path argument. If multiple root paths are provided, relative_path is automatically ignored and absolute paths are kept to avoid ambiguity.
matches	Logical. If TRUE, all matches per line are also returned in a matches list-column.
files	A character vector of files to search (only for seek_in()).

Details

The overall process involves the following steps:

• File Selection

  • seek(): Files are discovered using fs::dir_ls(), starting from one or more directories.

  • seek_in(): Files are directly supplied by the user (no discovery phase).

• File Filtering

  • Files located inside ⁠.git/⁠ folders are automatically excluded.

  • Files with known non-text extensions (e.g., .png, .exe, .rds) are excluded.

  • If a file's extension is unknown, a check is performed to detect embedded null bytes (binary indicator).

  • Optionally, an additional regex-based path filter (filter) can be applied.

• Line Reading

  • Files are read line-by-line using readr::read_lines().

  • Only lines matching the provided regular expression pattern are retained.

  • If a file cannot be read, it is skipped gracefully without failing the process.

• Data Frame Construction

  • A tibble is constructed with one row per matched line.

These functions are particularly useful for analyzing source code, configuration files, logs, and other structured text data.

Value

A tibble with one row per matched line, containing:

• path: File path (relative or absolute).

• line_number: Line number in the file.

• match: The first matched substring.

• matches: All matched substrings (if matches = TRUE).

• line: Full content of the matching line.

See Also

fs::dir_ls(), readr::read_lines(), stringr::str_detect()

Examples

path = system.file("extdata", package = "seekr")

# Search all function definitions in R files
seek("[^\\s]+(?= (=|<-) function\\()", path, filter = "\\.R$")

# Search for usage of "TODO" comments in source code in a case insensitive way
seek("(?i)TODO", path, filter = "\\.R$")

# Search for error/warning in log files
seek("(?i)error", path, filter = "\\.log$")

# Search for config keys in YAML
seek("database:", path, filter = "\\.ya?ml$")

# Looking for "length" in all types of text files
seek("(?i)length", path)

# Search for specific CSV headers using seek_in() and reading only the first line
csv_files <- list.files(path, "\\.csv$", full.names = TRUE)
seek_in(csv_files, "(?i)specie", n_max = 1)

seekr documentation built on June 8, 2025, 11:13 a.m.