Object Reference : Object View and Procedure Reference : Series
Fill in missing values, or NAs, within a series by interpolating from values that are not missing.
series_name.ipolate(options) series_name
type = key
Specify the interpolation method. key is either “lin” (linear, default), “log” (log-linear), “cs” (Cardinal spline), “cr” (Catmull-Rom spline), “cb” (Cubic spline), “lcs” (log-cardinal spline), “lcr” (log-Catmull-Rom spline), or “lcb” (log-cubic spline).
tension = number
Sets the tension parameter for the Cardinal spline method of interpolation. number should be a number between 0 and 1.
f = arg (default = “actual”)
Out-of-sample fill behavior: “actual” (fill observations
outside the interpolated sample with values from the source series). “na” (fill observations outside the sample with missing values”
Force the dialog to appear from within a program.
The following lines interpolate the missing values of series X1 using linear interpolation, and store the new interpolated series with a name X_INTER:
x1.ipolate x_inter
This line performs the same interpolation, but this time using the Cardinal spline, with a tension value of 0.8:
x1.ipolate(type=cs, tension=0.8) x_inter
See “Interpolate” for discussion.