> For the complete documentation index, see [llms.txt](https://dev.ubidots.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://dev.ubidots.com/synthetic-variables/expressions/date-range.md). # Date range Below are the most common date range functions. | Function | Description | | :-----------------: | :--------------------------------------------------------------------------------: | | $$max(x, range)$$ | Returns the maximum value of the variable x in the specified date range. | | $$min(x, range)$$ | Returns the minimum value of the variable x in the specified date range. | | $$mean(x, range)$$ | Returns the mean value of the variable x in the specified date range. | | $$std(x, range)$$ | Returns the standard deviation of the variable x in the specified date range. | | $$count(x, range)$$ | Returns the number of dots stored in the variable x for the specified date range. | | $$last(x, range)$$ | Returns the last value of the time-series variable x in the specified date range. | | $$first(x, range)$$ | Returns the first value of the time-series variable x in the specified date range. | | $$sum(x, range)$$ | Returns the sum of the dots stored in the variable x in the specified date range. | Date range functions use the following syntax: ***`aggregation_method(, , , )`*** | Parameters | Description | Value | Mandatory | | :--------: | :------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------: | :--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------: | :-------: | | Variable | Represents the measurements of a sensor as a [time series](https://docs.ubidots.com/v1.6/reference/time-series) of data points that vary over time. Also known as ["dots"](https://help.ubidots.com/en/articles/636672-plans-billing-what-are-dots), it is identified by a variable label. | Variable label | YES | | Range |

The time window in which the function is computed.

Note: Set the selected range so it evenly divides the next range. For example, if you use minutes ("T"), the number n must evenly divide an hour ("H"). Available minute values are 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, and 30. Other values may produce unexpected results. The same applies to other ranges.

|

Available data ranges:

This is a positive integer that represents the number of observations used for each window, or a time range specified as follows:

"nT": Every n minutes

"nH": Every n hours

"nD": Every n days

"W": Every end of the week

"M": Every end of the month

| YES | | Position | Indicates whether the output value is timestamped at the start or at the end of the time series. | `position = "start"` or `position = "end"` | NO | | Offset | Sets the hour at which the synthetic variable engine starts computing the variable. This value represents the number of hours after midnight. By default, it is 0. | Any integer between 1 and 23 | NO | --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter: ``` GET https://dev.ubidots.com/synthetic-variables/expressions/date-range.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.