# summarize operator

Produces a table that aggregates the content of the input table.

```
Sales | summarize NumTransactions=count(), Total=sum(UnitPrice * NumUnits) by Fruit, StartOfMonth=startofmonth(SellDateTime)
```

Returns a table with how many sell transactions and the total amount per fruit and sell month. The output columns show the count of transactions, transaction worth, fruit, and the datetime of the beginning of the month in which the transaction was recorded.

```
T | summarize count() by price_range=bin(price, 10.0)
```

A table that shows how many items have prices in each interval [0,10.0], [10.0,20.0], and so on. This example has a column for the count and one for the price range. All other input columns are ignored.

## Syntax

*T* `| summarize`

[[*Column* `=`

] *Aggregation* [`,`

...]]
[`by`

[*Column* `=`

] *GroupExpression* [`,`

...]]

## Arguments

*Column:*Optional name for a result column. Defaults to a name derived from the expression.*Aggregation:*A call to an aggregation function such as`count()`

or`avg()`

, with column names as arguments. See the list of aggregation functions.*GroupExpression:*A scalar expression that can reference the input data. The output will have as many records as there are distinct values of all the group expressions.

Note

When the input table is empty, the output depends on whether *GroupExpression*
is used:

- If
*GroupExpression*is not provided, the output will be a single (empty) row. - If
*GroupExpression*is provided, the output will have no rows.

## Returns

The input rows are arranged into groups having the same values of the `by`

expressions. Then the specified aggregation functions are computed over each group, producing a row for each group. The result contains the `by`

columns and also at least one column for each computed aggregate. (Some aggregation functions return multiple columns.)

The result has as many rows as there are distinct combinations of `by`

values
(which may be zero). If there are no group keys provided, the result has a single
record.

To summarize over ranges of numeric values, use `bin()`

to reduce ranges to discrete values.

Note

- Although you can provide arbitrary expressions for both the aggregation and grouping expressions, it's more efficient to use simple column names, or apply
`bin()`

to a numeric column. - The automatic hourly bins for datetime columns is no longer supported. Use explicit binning instead. For example,
`summarize by bin(timestamp, 1h)`

.

## List of aggregation functions

Function | Description |
---|---|

any() | Returns a random non-empty value for the group |

anyif() | Returns a random non-empty value for the group (with predicate) |

arg_max() | Returns one or more expressions when the argument is maximized |

arg_min() | Returns one or more expressions when the argument is minimized |

avg() | Returns an average value across the group |

avgif() | Returns an average value across the group (with predicate) |

binary_all_and | Returns aggregated value using the binary `AND` of the group |

binary_all_or | Returns aggregated value using the binary `OR` of the group |

binary_all_xor | Returns aggregated value using the binary `XOR` of the group |

buildschema() | Returns the minimal schema that admits all values of the `dynamic` input |

count() | Returns a count of the group |

countif() | Returns a count with the predicate of the group |

dcount() | Returns an approximate distinct count of the group elements |

dcountif() | Returns an approximate distinct count of the group elements (with predicate) |

make_bag() | Returns a property bag of dynamic values within the group |

make_bag_if() | Returns a property bag of dynamic values within the group (with predicate) |

make_list() | Returns a list of all the values within the group |

make_list_if() | Returns a list of all the values within the group (with predicate) |

make_list_with_nulls() | Returns a list of all the values within the group, including null values |

make_set() | Returns a set of distinct values within the group |

make_set_if() | Returns a set of distinct values within the group (with predicate) |

max() | Returns the maximum value across the group |

maxif() | Returns the maximum value across the group (with predicate) |

min() | Returns the minimum value across the group |

minif() | Returns the minimum value across the group (with predicate) |

percentiles() | Returns the percentile approximate of the group |

percentiles_array() | Returns the percentiles approximates of the group |

percentilesw() | Returns the weighted percentile approximate of the group |

percentilesw_array() | Returns the weighted percentiles approximates of the group |

stdev() | Returns the standard deviation across the group |

stdevif() | Returns the standard deviation across the group (with predicate) |

sum() | Returns the sum of the elements within the group |

sumif() | Returns the sum of the elements within the group (with predicate) |

variance() | Returns the variance across the group |

varianceif() | Returns the variance across the group (with predicate) |

## Aggregates default values

The following table summarizes the default values of aggregations:

Operator | Default value |
---|---|

`count()` , `countif()` , `dcount()` , `dcountif()` |
0 |

`make_bag()` , `make_bag_if()` , `make_list()` , `make_list_if()` , `make_set()` , `make_set_if()` |
empty dynamic array ([]) |

All others | null |

When using these aggregates over entities which includes null values, the null values will be ignored and won't participate in the calculation (see examples below).

## Examples

## Example: Unique combination

Determine what unique combinations of
`ActivityType`

and `CompletionStatus`

there are in a table. There are no aggregation functions, just group-by keys. The output will just show the columns for those results:

```
Activities | summarize by ActivityType, completionStatus
```

`ActivityType` |
`completionStatus` |
---|---|

`dancing` |
`started` |

`singing` |
`started` |

`dancing` |
`abandoned` |

`singing` |
`completed` |

## Example: Minimum and maximum timestamp

Finds the minimum and maximum timestamp of all records in the Activities table. There is no group-by clause, so there is just one row in the output:

```
Activities | summarize Min = min(Timestamp), Max = max(Timestamp)
```

`Min` |
`Max` |
---|---|

`1975-06-09 09:21:45` |
`2015-12-24 23:45:00` |

## Example: Distinct count

Create a row for each continent, showing a count of the cities in which activities occur. Because there are few values for "continent", no grouping function is needed in the 'by' clause:

```
Activities | summarize cities=dcount(city) by continent
```

`cities` |
`continent` |
---|---|

`4290` |
`Asia` |

`3267` |
`Europe` |

`2673` |
`North America` |

## Example: Histogram

The following example calculates a histogram for each activity
type. Because `Duration`

has many values, use `bin`

to group its values into 10-minute intervals:

```
Activities | summarize count() by ActivityType, length=bin(Duration, 10m)
```

`count_` |
`ActivityType` |
`length` |
---|---|---|

`354` |
`dancing` |
`0:00:00.000` |

`23` |
`singing` |
`0:00:00.000` |

`2717` |
`dancing` |
`0:10:00.000` |

`341` |
`singing` |
`0:10:00.000` |

`725` |
`dancing` |
`0:20:00.000` |

`2876` |
`singing` |
`0:20:00.000` |

... |

**Example for the aggregates default values**

When the input of `summarize`

operator has at least one empty group-by key, it's result is empty, too.

When the input of `summarize`

operator doesn't have an empty group-by key, the result is the default values of the aggregates used in the `summarize`

:

```
datatable(x:long)[]
| summarize any(x), arg_max(x, x), arg_min(x, x), avg(x), buildschema(todynamic(tostring(x))), max(x), min(x), percentile(x, 55), hll(x) ,stdev(x), sum(x), sumif(x, x > 0), tdigest(x), variance(x)
```

any_x | max_x | max_x_x | min_x | min_x_x | avg_x | schema_x | max_x1 | min_x1 | percentile_x_55 | hll_x | stdev_x | sum_x | sumif_x | tdigest_x | variance_x |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|

```
datatable(x:long)[]
| summarize count(x), countif(x > 0) , dcount(x), dcountif(x, x > 0)
```

count_x | countif_ | dcount_x | dcountif_x |
---|---|---|---|

0 | 0 | 0 | 0 |

```
datatable(x:long)[]
| summarize make_set(x), make_list(x)
```

set_x | list_x |
---|---|

[] | [] |

The aggregate avg sums all the non-nulls and counts only those which participated in the calculation (will not take nulls into account).

```
range x from 1 to 2 step 1
| extend y = iff(x == 1, real(null), real(5))
| summarize sum(y), avg(y)
```

sum_y | avg_y |
---|---|

5 | 5 |

The regular count will count nulls:

```
range x from 1 to 2 step 1
| extend y = iff(x == 1, real(null), real(5))
| summarize count(y)
```

count_y |
---|

2 |

```
range x from 1 to 2 step 1
| extend y = iff(x == 1, real(null), real(5))
| summarize make_set(y), make_set(y)
```

set_y | set_y1 |
---|---|

[5.0] | [5.0] |