| isolation_range | string | | Offset string. The range, within there are no valid values allowed for a valuegroup to get flagged isolated. See condition (1) and (2).|
| max_isolated_group_size | integer | `1` | The upper bound for the size of a value group to be considered an isolated group. See condition (3).|
| continuation_range | string | `"1min"` | Offset string. The upper bound for the temporal extension of a value group to be considered an isolated group. See condition (4). Only relevant if `max_islated_group_size` > 1.|
| drop_flags | list or Nonetype| `None` | A list of flags, that are to be considered, signifying invalid values. See condition (1) and (2).|
### Description
The function flags isolated values / value groups.
Isolated values are values / value groups,
that, in a range of `isolation_range`,
are surrounded either by invalid values only, or by no values.
The function defaults to flag isolated single values only. But the parameters
allow for detections of more complex isolation definitions, including groups
of isolated values.
A continuous group of values
$`x_{k}, x_{k+1},...,x_{k+n}`$ of the timeseries of meassurements $`x`$,
is considered "isolated", if:
1. There are no values, preceeding $`x_{k}`$ within `isolation_range` or all the
preceeding values within this range are flagged with a flag listed in
`drop_list`.
2. There are no values, succeeding $`x_{k+n}`$, within `isolation_range`, or all the
succeeding values within this range are flagged with a flag listed in
`drop_list`.
3. $`n \leq `$ `max_isolated_group_size`
4. $` |y_{k} - y_{n+k}| < `$ `continuation_range`, with $`y `$, denoting the series