Given a TimeSeries object ts, how do I implement ExpandingMap similar to MovingMap, where the window is not moving but expanding. In pseudocode,

tsNew[tf] = f[TimeSeriesWindow[ts,{t0,tf}]],

where t0=Min[ts["FirstTimes"]].

For example, the function Accumulate does exactly this with f=Total. I would like to have this functionality for an arbitrary function f.

Given a TimeSeries object ts, how do I implement ExpandingMap similar to MovingMap, where the window is not moving but expanding. In pseudocode,

tsNew[tf] = f[TimeSeriesWindow[ts,{t0,tf}]],

where t0=Min[ts["FirstTimes"]].

For example, the function Accumulate does exactly this with f=Total. I would like to have this functionality for an arbitrary function f.

Given a TimeSeries object ts, how do I implement ExpandingMap similar to MovingMap, where the window is not moving but expanding. In pseudocode,

tsNew[tf] = f[TimeSeriesWindow[ts,{t0,tf}]],

where t0=Min[ts["FirstTimes"]].

For example, the function Accumulate does exactly this with f=Total. I would like to have this functionality for an arbitrary function f.

Given a TimeSeries object ts, how do I implement ExpandingMap similar to MovingMap, where the window is not moving but expanding. In pseudocode,

tsNew[tf] = f[TimeSeriesWindow[ts,{t0,tf}]],

where t0=Min[ts["FirstTimes"]].

For example, the function Accumulate does exactly this with f=Total. I would like to have this functionality for an arbitrary function f.