ct_get_hs: Retrieve hierarchical subject (hs) values from image metadata

In ct: Camera Trap Data Management and Multi-Method Ecological Analysis

Retrieve hierarchical subject (hs) values from image metadata

Description

Extracts hierarchical subject metadata from image files using ExifTool. Hierarchical subjects follow a parent|child structure (e.g., "Species|Vulture") and are commonly used for taxonomic or categorical image classification.

Usage

ct_get_hs(path, hs_delimitor = "|", into_tibble = FALSE)

Arguments

path	A character string specifying the full path to the image file. Must be a valid file path to an image with EXIF metadata support.
hs_delimitor	The character delimiting hierarchy levels in image metadata tags in field "HierarchicalSubject"
into_tibble	Logical. Parse hierarchical subjects into tibble.

Value

A character vector or tibble of unique hierarchical subjects if they exist, otherwise NULL. Each element represents one hierarchical subject in "parent|child" format.

See Also

• ct_create_hs() to add hierarchical subjects

• ct_remove_hs() to remove hierarchical subjects

• ct_read_metadata() to read image metadata

Examples

## Not run: 
# Path to example image
image_path <- file.path(system.file("img", package = "ct"), "large.jpeg")

# Retrieve hierarchical subjects (returns NULL if none exist)
hs <- ct_get_hs(path = image_path)
print(hs)

# After adding hierarchical subjects
ct_create_hs(path = image_path, value = c("Species" = "Vulture"))
ct_get_hs(path = image_path)  # Returns: "Species|Vulture"

# Multiple hierarchical subjects
ct_create_hs(
  path = image_path,
  value = c("Species" = "Eagle", "Location" = "Mountains")
)
ct_get_hs(path = image_path)  # Returns vector with both subjects

## End(Not run)

ct documentation built on Oct. 22, 2026, 1:07 a.m.