cummax()

cummax(x)

Returns: numeric · Updated March 13, 2026 · Base Functions

cumulative vectors cummax base

The cummax() function computes the cumulative maximum of a vector, returning a vector of the same length where each element is the maximum of all preceding elements.

Syntax

cummax(x)

Parameters

Parameter	Type	Default	Description
`x`	numeric	required	A numeric vector

Examples

Basic usage

x <- c(1, 2, 3, 4, 5)

cummax(x)
# [1] 1 2 3 4 5

# With decreasing values
y <- c(5, 4, 3, 2, 1)
cummax(y)
# [1] 5 5 5 5 5

# With mixed values
z <- c(3, 1, 4, 1, 5)
cummax(z)
# [1] 3 3 4 4 5

Tracking running maximum

# Sales data
sales <- c(100, 150, 80, 200, 175)

# Running maximum revenue
cummax(sales)
# [1] 100 150 150 200 200

Common Patterns

Peak detection

# Stock prices
prices <- c(100, 95, 105, 98, 110, 105, 115)

# All-time highs
cummax(prices)
# [1] 100 100 105 105 110 110 115

Performance tracking

# Test scores over time
scores <- c(85, 78, 92, 88, 95, 90, 98)

# Best score so far
cummax(scores)
# [1] 85 85 92 92 95 95 98