Package google.api

Index

Distribution

Distribution contains summary statistics for a population of values. It optionally contains a histogram representing the distribution of those values across a set of buckets.

The summary statistics are the count, mean, sum of the squared deviation from the mean, the minimum, and the maximum of the set of population of values. The histogram is based on a sequence of buckets and gives a count of values that fall into each bucket. The boundaries of the buckets are given either explicitly or by formulas for buckets of fixed or exponentially increasing widths.

Although it is not forbidden, it is generally a bad idea to include non-finite values (infinities or NaNs) in the population of values, as this will render the mean and sum_of_squared_deviation fields meaningless.

Fields
count

int64

The number of values in the population. Must be non-negative. This value must equal the sum of the values in bucket_counts if a histogram is provided.

mean

double

The arithmetic mean of the values in the population. If count is zero then this field must be zero.

sum_of_squared_deviation

double

The sum of squared deviations from the mean of the values in the population. For values x_i this is:

Sum[i=1..n]((x_i - mean)^2)

Knuth, "The Art of Computer Programming", Vol. 2, page 232, 3rd edition describes Welford's method for accumulating this sum in one pass.

If count is zero then this field must be zero.

range

Range

If specified, contains the range of the population values. The field must not be present if the count is zero.

bucket_options

BucketOptions

Defines the histogram bucket boundaries. If the distribution does not contain a histogram, then omit this field.

bucket_counts[]

int64

The number of values in each bucket of the histogram, as described in bucket_options. If the distribution does not have a histogram, then omit this field. If there is a histogram, then the sum of the values in bucket_counts must equal the value in the count field of the distribution.

If present, bucket_counts should contain N values, where N is the number of buckets specified in bucket_options. If you supply fewer than N values, the remaining values are assumed to be 0.

The order of the values in bucket_counts follows the bucket numbering schemes described for the three bucket types. The first value must be the count for the underflow bucket (number 0). The next N-2 values are the counts for the finite buckets (number 1 through N-2). The N'th value in bucket_counts is the count for the overflow bucket (number N-1).

exemplars[]

Exemplar

Must be in increasing order of value field.

BucketOptions

BucketOptions describes the bucket boundaries used to create a histogram for the distribution. The buckets can be in a linear sequence, an exponential sequence, or each bucket can be specified explicitly. BucketOptions does not include the number of values in each bucket.

A bucket has an inclusive lower bound and exclusive upper bound for the values that are counted for that bucket. The upper bound of a bucket must be strictly greater than the lower bound. The sequence of N buckets for a distribution consists of an underflow bucket (number 0), zero or more finite buckets (number 1 through N - 2) and an overflow bucket (number N - 1). The buckets are contiguous: the lower bound of bucket i (i > 0) is the same as the upper bound of bucket i - 1. The buckets span the whole range of finite values: lower bound of the underflow bucket is -infinity and the upper bound of the overflow bucket is +infinity. The finite buckets are so-called because both bounds are finite.

Fields
Union field options. Exactly one of these three fields must be set. options can be only one of the following:
linear_buckets

Linear

The linear bucket.

exponential_buckets