- The Quantitative Supply Chain Manifesto
- The Lokad test of supply chain performance
- An overview of quantitative supply chain
- Generalized probabilistic forecasting
- Decision-driven optimization
- Economic drivers
- Data preparation
- The Supply Chain Scientist
- Timeline of a typical project
- Project deliverables
- Assessing success
- Antipatterns in supply chain

- Inventory forecasting
- Prioritized ordering report
- Old forecasting input file format
- Old forecasting output file format
- Choosing the service levels
- Managing your inventory settings
- The old Excel forecast report
- Using tags to improve accuracy
- Oddities in classic forecasts
- Oddities in quantile forecasts
- Stock-out's bias on quantile forecasts
- Daily, weekly and monthly aggregations

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The aggregators are similar to functions, but they benefit from a richer syntax with options. Below, we list the aggregators supported by Envision.

`agg`

is:
u = agg(v) by [w1, w2, w3] sort [w4, w5] if c or x over [a .. b]Where:

`agg`

is the name of the aggregator.`by`

is an option indicating the groups to be used when aggregating. It is possible to aggregate against one or more values.`sort`

is an option indicating the sorting order to be used when aggregating. It is possible to sort against one or more values.`if`

is an aggregator filter. When present, all lines that are`false`

are omitted from the aggregation.`or`

is an option indicating the value to return if the group is empty.`over`

is an option used to define an aggregation time-span with boundaries expressed in days and relative to the date of the target line.

When

`by`

is not specified, the grouping happens according to the context, typically using the left-side of the statement in the case of an assignment. It is possible to list multiple variables after `by`

; if only one variable is used, then the parentheses are not required.The

`sort`

option has typically no impact on most aggregators, e.g. `max`

, because those operators do not depend on any sort order in the first place. However, we suggest to leverage this option with `first`

and `last`

aggregators.When

`if`

is not specified, all lines are included which is equivalent to `if true`

.When

`or`

is not specified, default values are returned when the grouping is empty: `0`

(zero) for number, `false`

for booleans, the empty string for text and the zero distribution for distributions.u = agg(v) by [w1, w2, w3] sort [w4, w5] if c at [z1, z2, z3] or x

The

`at`

option indicates the groups used when joining the tables. Note that there must be a one-to-one correspondence between these groups and the groups used in the `by`

option. As a consequence, the `by`

option is mandatory and the number of entries specified in the `by`

and in the `at`

options must be identical.`avg`

: numeric argument only; returns the average line value.`count`

: counts the number of lines that are either`true`

(booleans) or non-zero (numbers) or non-empty (text).`distinct`

: counts the number of distinct values.`first`

: returns the value associated to the earliest line, as defined per the`sort`

option.`last`

: returns the value associated to the latest line, as defined per the`sort`

option.`max`

: returns the highest value.`median`

: behaves like the MEDIAN function is Excel.`min`

: returns the lowest value.`product`

: numeric argument only; returns the product of line values.`ratio`

: returns the percentage (between 0 and 1) of Booleans that are true, or of numbers that are non-zero. The ratio of an empty group is 1.`same`

: expects all the grouped values to be identical (fails otherwise) and returns this value.`sum`

: numeric argument only; returns the sum of line values.

`all`

: returns`true`

if all the input lines are`true`

and return`false`

otherwise.`any`

: returns`false`

if all the input lines are`false`

and return`true`

otherwise.`exists`

: returns`true`

if there is at least one line passed to the aggregator.

`Date`

column:`latest`

(cross-table, special case): returns the most recent value observed.`latest`

is not compatible with any of the available options.

`entropy`

: returns the Shannon Entropy of the group. The value is returned expressed in*shannons*.`mode`

: similar to the MODE function in Excel.`percentile`

(two arguments, special case): similar to the PERCENTILE function in Excel. The second argument is percentile target between 0 and 1.`stdev`

: similar to the STDEV function in Excel.`stdevp`

: similar to the STDEV.P function in Excel.

`ranvar`

: returns the empirical random variable associated to the numeric observations.`sumr`

: returns the sum of additive convolutions of random variables. Just like`sum()`

is the aggregator associated to the`+`

operator, the aggregator`sumr()`

is associated to the`+*`

operator.