WIDTH_BUCKET

For a given expression, the WIDTH_BUCKET function returns the bucket number into which the value of this expression would fall after being evaluated.

Return Value

An INTEGER.

Syntax

WIDTH_BUCKET (expr , min_value , max_value , num_buckets)

Arguments

expr

The expression for which the histogram is being created. This expression must evaluate to a number or a datetime value. When expr evaluates to NA, then the expression returns NA.

min_value

An expression that resolves to the minimum end point of the acceptable range for expr. This expression must evaluate to number or datetime values, and cannot evaluate to NA.

max_value

An expression that resolves to the maximum end point of the acceptable range for expr. This expression must evaluate to number or datetime values, and cannot evaluate to NA.

num_buckets

An expression that resolves to a constant indicating the number of buckets. This expression must evaluate to a positive INTEGER.

Notes

Underflow Bucket

The function also creates (when needed) an underflow bucket numbered 0 and an overflow bucket numbered num_buckets+1. These buckets handle values less than min_value and more than max_value and are helpful in checking the reasonableness of endpoints.

Notes

Constructing Equiwidth Histograms

WIDTH_BUCKET lets you construct equiwidth histograms, in which the histogram range is divided into intervals that have identical size. (Compare this function with NTILE, which creates equiheight histograms.) Ideally each bucket is a "closed-open" interval of the real number line. For example, a bucket can be assigned to cores between 10.00 and 19.999... to indicate that 10 is included in the interval and 20 is excluded. This is sometimes denoted (10, 20).