Change data form Table to Array

Question

Ok, I am trying to figure out how exactly to change the data from Table such as

ptopp = Transpose[{pressure[[All, 1]], pressure[[All, 2]]}]
(* {{0., 59.5}, {0.1, 30.7}, {0.2, 
  21.1}, {0.3, -7.73}, {0.4, -17.3}, {1., -36.6}, {5., -75.}, {8., \
-104.}, {10., -123.}, {15., -94.2}, {20., -65.4}, {35., -36.6}, {65., \
-7.73}, {100., 1.87}} *)

into an Array. And I want to do that because I have to fit some function to that and I think it might be the best idea to use ListInterpolation which requires Array. There is something written about including the x component into the Array here: https://reference.wolfram.com/language/ref/ListInterpolation.html but I don't really understand how to convert it from a table to the desired form. Could semobody help?

Answer 1

The second argument to ListInterpolation can either be a range of x-values (assumed to be equally spaced) or a list of x-values corresponding to the list values. So in your case you may simply do

ListInterpolation[ pressure[[All,2]] , pressure[[All,1]] ]

Or simply use

Interpolation[ptopp]

for the same result, or

InterpolatingPolynomial[ptopp,x]

if you want a polynomial instead of an InterpolatingFunction