These are aggregate functions as available on stream views and pipes. Aggregate functions serve the purpose of aggregating data and giving it more eaningfull meaning. They are usually a common feature in any data based environment. In database management, for instance aggregate functions are used where multiple rows are grouped together to form a singe value or to find out more significant meaning, represented by a single value on a set of values.
Aggregate functions are also available on pipes and views in PhixFlow. The following composes a set of available functions (all aggregate function below expect a single argument - field name):
| Function | Description | ||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| average | This function returns the arithmetic average of the set of numbers. It takes one argument (a name of a field to aggregate on) of numeric type: Long, Float or Integer. It is only available if field on which it is applied, is of such type. | ||||||||||||||||||||||
| maximum | This function returns the maximum numeric value out of the set of numeric, dates as well as string values. It takes one argument (a name of a field to aggregate on) of type, either: Long, Float, Integer or a String. In case of a String, it will return a "maximum string", that is a string that would be the last string out of the whole set of strings, if they were sorted in alphabetical order. In case of a date - it will return the latest date. | ||||||||||||||||||||||
| minimum | This function returns the minimum numeric value out of the set of numeric, dates as well as string values. It takes one argument (a name of a field to aggregate on) of type, either: Long, Float, Integer or a String. In case of a String, it will return a "minimum string", that is a string that would be the first string out of the whole set of strings, if they were sorted in alphabetical order. In case of a date - it will return the earliest date. | ||||||||||||||||||||||
| sum | This function returns the sum calculated by suming all the values in a given set of values. It is applicable only (and only then it is available) if the name of the field passed to this function represents numeric field of type: Long, Float or Integer. | ||||||||||||||||||||||
| percent | This function expects a name of numeric field to calculate percentage of sum of numerical values of each group in relation to a whole set of grouped values. It is therefore necessary to use this function in conjunction with grouping attribute, as otherwise only default grouping would be applied and this would present no meaningful result, as it would always default to 100% (each record would have been in its own group). If however we assume having a file with 2 records, like so:
and we also assume grouping by "Label", our percent function would return (if applied o "Number" attribute), the following result in a view (assuming we also selected Label attribute to be shown in our view and rounding to 2 decimal places):
The above are percentages of values assigned to given grouping parameters (A, B, C) as a percentage portion of the whole, computed as sum of all such values. | ||||||||||||||||||||||
| distinct | Returns the number of unique values for the given attribute. | ||||||||||||||||||||||
| count | Counts the number of elements. |