spline

spline(X, Y, resampleRule, [closed='left'], [origin='start_day'], [outputX=false])

X is a strictly increasing vector of temporal type.

Y is a numeric vector of the same length as X.

resampleRule is a string. See the parameter rule of function resample for the optional values.

closed and origin (optional) are the same as the parameters closed and origin of function resample.

outputX (optional) is a Boolean value indicating whether to output the resampled X. The default value is false.

Resample X based on the specified resampleRule, closed and origin. Perform cubic spline interpolation on Y based on the resampled X.

If outputX is unspecified, return a vector of Y after the interpolation.

If outputX=true, return a tuple where the first element is the vector of resampled X and the second element is a vector of Y after the interpolation.

spline([2016.02.14 00:00:00, 2016.02.15 00:00:00, 2016.02.16 00:00:00], [1.0, 2.0, 4.0], resampleRule=`60min);

// output
[1,1.0313,1.0626,1.0942,1.1262,1.1585,1.1914,1.225,1.2593,1.2944,1.3306,1.3678,1.4062,1.446,1.4871,1.5298,1.5741,1.6201,1.668,1.7178
,1.7697,1.8237,1.8801,1.9388,2,2.0638,2.1301,2.1987,2.2697,2.3428,2.418,2.4951,2.5741,2.6548,2.7371,2.821,2.9062,2.9928,3.0806,3.1694
,3.2593,3.35,3.4414,3.5335,3.6262,3.7192,3.8126,3.9063,4]