Vectors and elementwise arithmetic

The idea

An atomic vector contains elements of one basic type, such as logical, integer, double, or character. The c function combines values into a vector and may coerce them to a common type. A single number is also a vector of length one. Use <- to bind a name to a value, and use == when asking whether values are equal rather than assigning a new value.

Arithmetic generally acts element by element. A length-one value is recycled across a longer vector, making transformations such as adding a constant concise. Recycling longer mismatched lengths can conceal mistakes even when R permits the operation, so verify the intended dimensions. Functions such as sum combine many values into one result, while length reports how many elements are present.

scores <- c(2, 5, 8)
adjusted <- scores + 1
cat(adjusted, sep = ",")
cat("
")
cat(sum(adjusted), "
", sep = "")

3,6,9
18

Adding one transforms each element independently. sum then reduces the three transformed values to a single total without changing the original scores vector.