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Replace Outliers

Source: R/outliers.R
replace_outliers.Rd

Replaces detected outliers with specified values such as NA, mean, median, or winsorized values. Supports multiple detection methods.

Usage

replace_outliers(
  data,
  Vars,
  detect = c("zscore", "iqr", "percentile"),
  threshold = NULL,
  replace_with = c("NA", "mean", "median", "winsorize", "boundary"),
  suffix = NULL
)

Arguments

data

A data frame.

Vars

Character vector of numeric variable names to process.

detect

Detection method: "zscore", "iqr", or "percentile".

threshold

Numeric threshold for detection. For zscore: number of SDs (default 3). Use 2 for 2SD, 2.5 for 2.5SD, etc. For iqr: IQR multiplier (default 1.5). For percentile: percentile cutoff (default 0.01 for 1st/99th).

replace_with

Replacement method: "NA", "mean", "median", "winsorize", or "boundary".

suffix

Character. Suffix for new columns. If NULL (default), replaces in place.

Value

Data frame with outliers replaced.

Details

Detection methods:

  • "zscore": Values beyond threshold SDs from mean. Common thresholds: 2, 2.5, 3, 3.29

  • "iqr": Values beyond Q1/Q3 +/- threshold*IQR. Common thresholds: 1.5, 3

  • "percentile": Values below or above percentile cutoffs. E.g., 0.01 = 1st/99th, 0.05 = 5th/95th

Replacement methods:

  • "NA": Set outliers to NA

  • "mean": Replace with mean of non-outliers

  • "median": Replace with median of non-outliers

  • "winsorize": Cap at threshold boundary

  • "boundary": Replace with nearest non-outlier value

Examples

if (FALSE) { # \dontrun{
df <- mtcars

# Replace outliers beyond 2 SD with NA
df_clean <- replace_outliers(df, Vars = "hp",
                             detect = "zscore", threshold = 2,
                             replace_with = "NA")

# Winsorize at 3 SD
df_clean <- replace_outliers(df, Vars = "hp",
                             detect = "zscore", threshold = 3,
                             replace_with = "winsorize")

# Replace outliers at 5th/95th percentile with median
df_clean <- replace_outliers(df, Vars = "hp",
                             detect = "percentile", threshold = 0.05,
                             replace_with = "median")

# IQR-based winsorization
df_clean <- replace_outliers(df, Vars = c("mpg", "hp"),
                             detect = "iqr", replace_with = "winsorize")
} # }