arg_max() (aggregation function)

Finds a row in the table that maximizes the specified expression. It returns all columns of the input table or specified columns.

Syntax

arg_max (ExprToMaximize, * | ExprToReturn [, …])

Parameters

Returns

Returns a row in the table that maximizes the specified expression ExprToMaximize, and the values of columns specified in ExprToReturn.

Examples

General examples

The following example finds the maximum latitude of a storm event in each state.

StormEvents 
| summarize arg_max(BeginLat, BeginLocation) by State

Output

The results table displays only the first 10 rows.

The following example finds the last time an event with a direct death happened in each state, showing all the columns.

The query first filters the events to include only those events where there was at least one direct death. Then the query returns the entire row with the most recent StartTime.

StormEvents
| where DeathsDirect > 0
| summarize arg_max(StartTime, *) by State

Output

The results table displays only the first 10 rows and first three columns.

The following example demonstrates null handling.

datatable(Fruit: string, Color: string, Version: int) [
    "Apple", "Red", 1,
    "Apple", "Green", int(null),
    "Banana", "Yellow", int(null),
    "Banana", "Green", int(null),
    "Pear", "Brown", 1,
    "Pear", "Green", 2,
]
| summarize arg_max(Version, *) by Fruit

Output

Examples comparing arg_max() and max()

The arg_max() function differs from the max() function. The arg_max() function allows you to return other columns along with the maximum value, and max() only returns the maximum value itself.

The following example uses arg_max() to find the last time an event with a direct death happened in each state, showing all the columns. The query first filters the events to only include events where there was at least one direct death. Then the query returns the entire row with the most recent (maximum) StartTime.

StormEvents
| where DeathsDirect > 0
| summarize arg_max(StartTime, *)

The results table returns all the columns for the row containing the highest value in the expression specified.

| StartTime | EndTime | EpisodeId | EventId | State | EventType | … | |–|–|–|–| | 2007-12-31T15:00:00Z | 2007-12-31T15:00:00 | 12688 | 69700 | UTAH | Avalanche | … |

The following example uses the max() function to find the last time an event with a direct death happened in each state, but only returns the maximum value of StartTime.

StormEvents
| where DeathsDirect > 0
| summarize max(StartTime)

The results table returns the maximum value of StartTime, without returning other columns for this record.

Related content

• Aggregation function types at a glance
• arg_min function
• max function
• avg function
• percentile function