sparkbar

The function plots a frequency histogram for values x and the repetition rate y of these values over the interval [min_x, max_x]. Repetitions for all x falling into the same bucket are averaged, so data should be pre-aggregated. Negative repetitions are ignored.

If no interval is specified, then the minimum x is used as the interval start, and the maximum x — as the interval end. Otherwise, values outside the interval are ignored.

Syntax

sparkbar(buckets[, min_x, max_x])(x, y)

Parameters

• buckets — The number of segments. Type: Integer.
• min_x — The interval start. Optional parameter.
• max_x — The interval end. Optional parameter.

Arguments

• x — The field with values.
• y — The field with the frequency of values.

Returned value

• The frequency histogram.

Example

Query:

CREATE TABLE spark_bar_data (`value` Int64, `event_date` Date) ENGINE = MergeTree ORDER BY event_date;

INSERT INTO spark_bar_data VALUES (1,'2020-01-01'), (3,'2020-01-02'), (4,'2020-01-02'), (-3,'2020-01-02'), (5,'2020-01-03'), (2,'2020-01-04'), (3,'2020-01-05'), (7,'2020-01-06'), (6,'2020-01-07'), (8,'2020-01-08'), (2,'2020-01-11');

SELECT sparkbar(9)(event_date,cnt) FROM (SELECT sum(value) as cnt, event_date FROM spark_bar_data GROUP BY event_date);

SELECT sparkbar(9, toDate('2020-01-01'), toDate('2020-01-10'))(event_date,cnt) FROM (SELECT sum(value) as cnt, event_date FROM spark_bar_data GROUP BY event_date);

Result:

┌─sparkbar(9)(event_date, cnt)─┐
│ ▂▅▂▃▆█  ▂                    │
└──────────────────────────────┘

┌─sparkbar(9, toDate('2020-01-01'), toDate('2020-01-10'))(event_date, cnt)─┐
│ ▂▅▂▃▇▆█                                                                  │
└──────────────────────────────────────────────────────────────────────────┘

The alias for this function is sparkBar.