# FlexMatch property expressions
Property expressions

Property expressions can be used to define certain matchmaking-related properties. They allow you to use calculations and logic when defining a property value. Property expressions generally result in one of two forms: 
+ Individual player data.
+ Calculated collections of individual player data.

## Common matchmaking property expressions


A property expression identifies a specific value for a player, team, or match. The following partial expressions illustrate how to identify teams and players: 


| Goal | Input | Meaning | Output | 
| --- | --- | --- | --- | 
| To identify a specific team in a match: | teams[red] | The Red team | Team  | 
| To identify a set of specific teams in a match: | teams[red,blue] | The Red team and the Blue team | List<Team> | 
| To identify all teams in a match: | teams[\$1] | All teams | List<Team> | 
| To identify players in a specific team: | team[red].players | Players in the Red team  | List<Player> | 
| To identify players in a set of specific teams in a match: | team[red,blue].players | Players in the match, grouped by team | List<List<Player>> | 
| To identify players in a match: | team[\$1].players | Players in the match, grouped by team | List<List<Player>> | 

## Property expression examples


The following table illustrates some property expressions that build on the previous examples:


****  

| Expression | Meaning | Resulting Type | 
| --- | --- | --- | 
|  `teams[red].players[playerId]`  | The player IDs of all players on the red team | List<string> | 
| teams[red].players.attributes[skill] | The "skill" attributes of all players on the red team | List<number> | 
| teams[red,blue].players.attributes[skill] | The "skill" attributes of all players on the Red team and the Blue team, grouped by team | List<List<number>> | 
| teams[\$1].players.attributes[skill] | The "skill" attributes of all players in the match, grouped by team | List<List<number>> | 

## Property expression aggregations


Property expressions can be used to aggregate team data by using the following functions or combinations of functions:


****  

| Aggregation | Input | Meaning | Output | 
| --- | --- | --- | --- | 
| min | List<number> | Get the minimum of all numbers in the list. | number | 
| max | List<number> | Get the maximum of all numbers in the list. | number | 
| avg | List<number> | Get the average of all numbers in the list. | number | 
| median | List<number> | Get the median of all numbers in the list. | number | 
| sum | List<number> | Get the sum of all numbers in the list. | number | 
| count | List<?> | Get the number of elements in the list. | number | 
| stddev | List<number> | Get the standard deviation of all numbers in the list. | number | 
| flatten | List<List<?>> | Turn a collection of nested lists into a single list containing all elements. | List<?> | 
| set\$1intersection | List<List<string>> | Get a list of strings that are found in all string lists in a collection. | List<string> | 
| All above | List<List<?>> | All operations on a nested list operate on each sublist individually to produce a list of results. | List<?> | 

The following table illustrates some valid property expressions that use aggregation functions: 


****  

| Expression | Meaning | Resulting Type | 
| --- | --- | --- | 
| flatten(teams[\$1].players.attributes[skill]) | The "skill" attributes of all players in the match (not grouped) | List<number> | 
| avg(teams[red].players.attributes[skill]) | The average skill of the red team players | number | 
| avg(teams[\$1].players.attributes[skill]) | The average skill of each team in the match | List<number> | 
| avg(flatten(teams[\$1].players.attributes[skill])) | The average skill level of all players in the match. This expression gets a flattened list of player skills and then averages them. | number | 
| count(teams[red].players) | The number of players on the red team | number | 
| count (teams[\$1].players) | The number of players on each team in the match | List<number> | 
| max(avg(teams[\$1].players.attributes[skill])) | The highest team skill level in the match  | number |