Check for Missing Values (NA) in Data

Identifies and reports the presence of missing values (NA) in vectors or two-dimensional data structures. Provides detailed positional information including row/column indices and names when available. Returns structured information for programmatic use while displaying user-friendly messages.

Usage

CheckNA(data, max_print = 5L, ...)

Arguments

data

A vector, matrix, data frame, or Matrix object to check for NA values.

max_print

Integer. Maximum number of NA positions to display in console output. Set to 0 to suppress position details. Default: 5L.

...

Additional arguments (currently unused, reserved for future extensions).

Value

Invisible list containing NA information:

count

Total number of NA values found

positions

For vectors: integer vector of positions; For 2D data: data frame with row/column indices and names (if available)

names

For named vectors: character vector of names corresponding to NA positions

Returns empty list components when no NA values are found.

Output Behavior

• No NAs found: Prints success message and returns empty list

• NAs found: Prints warning with count and up to max_print positions

• Position details: Includes row/column names when available for easier debugging

See also

is.na, complete.cases, na.omit

Examples

if (FALSE) { # \dontrun{
# Example 1: Vector with NAs
vec <- c(10, 20, NA, 40, NA, 60)
result <- CheckNA(vec)
# Output: Found 2 NA values
#         Positions: 3, 5

# Example 2: Named vector
named_vec <- c(Sample1 = 10, Sample2 = NA, Sample3 = 30, Sample4 = NA)
result <- CheckNA(named_vec)
# Output: Found 2 NA values
#         Positions: 2, 4
#         with names: Sample2, Sample4

# Example 3: Data frame with row and column names
df <- data.frame(
  Gene1 = c(1.0, 2.0, NA),
  Gene2 = c(NA, 2.5, 3.0),
  Gene3 = c(1.5, NA, 3.5),
  row.names = c("Cell1", "Cell2", "Cell3")
)
result <- CheckNA(df)
# Output: Found 3 NA values in data
#         First 3 positions:
#         Row 3 (Cell3), Col 1 (Gene1)
#         Row 1 (Cell1), Col 2 (Gene2)
#         Row 2 (Cell2), Col 3 (Gene3)

# Example 4: Matrix without names
mat <- matrix(c(1, NA, 3, 4, 5, NA), nrow = 2, ncol = 3)
result <- CheckNA(mat)
# Output: Found 2 NA values in data
#         First 2 positions:
#         Row 2, Col 1
#         Row 1, Col 3

# Example 5: No NAs found
clean_data <- c(1, 2, 3, 4, 5)
result <- CheckNA(clean_data)
# Output: No NA values found in the vector

# Example 6: Programmatic use - extract NA count
df <- data.frame(a = c(1, NA, 3), b = c(NA, 2, 3))
na_info <- CheckNA(df)
na_info$count  # Returns: 2
na_info$positions  # Returns: data frame with positions
} # }