Time Series

Time series are sets of data points. Each data point is a pair of a time stamp and a value.

Time Stamps

A time stamp is any point in time. We support 1-second resolution, and a time range from year -100,000 to 100,000. We use the ISO 8601 calendar definition, which is basically a mathematically sound version of the Gregorian Calendar, without "there is no year zero" and similar nonsense, and which pretends - perhaps in an overly optimistic generalization - that thousands of years ago they had the same weekends, the same lengths of months, and the same leap year rules which we have today.

Data Point Values

Values are just floating point numbers. You may speficy a unit for your values, but that's only for displaying them. We don't do any calculations based on units. You may also define decimal places for your values, but again that's only for displaying them, not for storage.

Types of Time Series

There are two types of time series. The first type is called "stored time series", and is defined by its set of data points. The second type is "derived time series", whose data points are calculated from source time series by a formula.

Creating Time Series

You can create a new stored time series in the time series menu by just giving it a name. Optionally, you can say which unit should be used for the values. The unit will be shown in lists and in charts.

Derived time series are created by first selecting the source series, and then writing the formula used to calculate the new series.

Time Zones

Each time series has a time zone, by default the time zone setting of your browser. Time zones are important when showing data points and when doing calculations. Internally, we store all time stamps in unambiguous UTC. That means, when you change the time zone of a time series, you only change the time shown in the output.

Time zones can be quite tricky when doing calculations for derived time series. Think of daylight saving time and the different lengths of months. We handle all of that complexity for you, but you need to be aware that sometimes you might see slightly surprising results when dealing with edge cases (which time is one month after Jan 30 12:00?).

Populating Stored Time Series

There are three ways to get data points into the system.

Manual Entry

You can enter a time stamp in one of the supported formats and a value in a form. If you don't spefify a time zone when entering the time stamp, the time zone of the time series is used.

Import from a CSV File

If you have a CSV file holding data points, you can upload it into a stored time series.

Time Series Post API

Our API supports posting data points.

Data Point Limit

A stored time series can only hold a certain number of data points. The limit for free accounts is 10,000 points. Paid plans support up to 10m data points per time series. If you try to add data points beyond that limit, you need to specify what to do to stay within the limit. One option is to let us delete the oldest data point whenever a new one is added.