which.max / which.min()

which.min(x) / which.max(x)

which.min() and which.max() are base R functions that return the index of the minimum and maximum values in a vector respectively. They are essential tools for finding the position of extreme values without having to manually scan through entire vectors.

Syntax

which.min(x)
which.max(x)

Parameters

Parameter	Type	Description
x	numeric or character	A vector of numeric or character values

Examples

Basic usage with numeric vectors

scores <- c(85, 92, 78, 88, 95)

# Find position of minimum value
which.min(scores)
# [1] 3

# Find position of maximum value
which.max(scores)
# [1] 5

Using with character vectors

fruits <- c("apple", "banana", "cherry", "date")

# Find first alphabetically
which.min(fruits)
# [1] 1  (apple)

# Find last alphabetically
which.max(fruits)
# [1] 4  (date)

Finding extreme values with their positions

temperatures <- c(72, 68, 75, 71, 69, 82, 77)

# Get the index of the coldest and warmest days
coldest <- which.min(temperatures)
warmest <- which.max(temperatures)

# Extract the values
temperatures[coldest]
# [1] 68

temperatures[warmest]
# [1] 82

Using with data frames

df <- data.frame(
  product = c("A", "B", "C", "D"),
  price = c(29.99, 45.00, 19.99, 35.50)
)

# Find cheapest product
df[which.min(df)]
# [1] "C"

# Find most expensive product  
df[which.max(df)]
# [1] "B"

Common Patterns

Combining with order() for sorting

values <- c(5, 2, 8, 1, 9, 3)

# Get indices of min and max
c(min = which.min(values), max = which.max(values))
# min max 
#   4   5

Finding extremes in matrices

m <- matrix(1:9, nrow = 3)
#      [,1] [,2] [,3]
# [1,]    1    4    7
# [2,]    2    5    8
# [3,]    3    6    9

which.min(m)
# [1] 1

which.max(m)
# [1] 9

Handling NA values

data <- c(1, NA, 5, 2, NA, 8)

# NA values are ignored by default
which.min(data)
# [1] 1

which.max(data)
# [1] 6

See Also

• base::which
• base::min
• base::range
• base::order