Using two vectors to scale a vector

Question

ParkerCambridge 2019-7-25

回答： Star Strider 2019-7-25

Hi,

I have three vectors of different scale, lets say

x1= (0:0.1:1)';
x2 = (0:1:10)';
x3 = [-0.01;0.99;2.01;2.98;3.99;5.001;5.99;7.021;8.001;8.999;10.11];

If I would like to scale x2 to x1, I can use interp1 function as

scaledx2 = interp1([min(x2),max(x2)],[min(x1),max(x1)],x2);

However, for x3 which is slightly different and has got some random noise on it. If I use the same interp1 function as

scaledx3 = interp1([min(x2),max(x2)],[min(x1),max(x1)],x3)

It understandbly gives me NAN values for the 1st and the last values which is incorrect. So how can I scale x3, based on the scales of x1 and x2?

Many Thanks

Answer 1

Star Strider 2019-7-25

The NaN values at the ends are because interp1 must extrapolate and needs to be told how to do it.

Try this:

scaledx3 = interp1([min(x2),max(x2)],[min(x1),max(x1)],x3, 'linear','extrap')

I use 'linear' here, although any method will work.