Smoothing data by x axis values rather than cells

I am trying to compare slope values from bathymetric profiles with different resolutions ranging from 30m to 85m. Therefore, I need to smooth the profiles to a common resolution (say 200 m). I attach an example of my data where c is depth (to smooth in m), d1 is distance (m) and the resolution is ~60 m. I can take 200/60 m to get a smoothing window in cells per 200 m then use smooth or filter. For example:

span=round(200/resolution);

smooth_bathy=smooth(c,span);

The problem is that the span or smoothing window has to be an integer so the smoothed resolution between profiles is still different i.e. 200/60 = 180 m and 200/35 =175 m.

Can anyone suggest a method to smooth the data to exacly 200 m (i.e. smooth by absoute values of the data in the x axis rather than cells?). Thanks.

[Mathieu NOE]

hello

it's a bit confusing when you say smoothing and resampling to common 200 m resolution; resampling and smoothing are separate topics.

if the question is how to resample all data to 200 m resolution (whatever your resolution is ), simply use interp1 :

new_d = min(d1):200:max(d1); % new distance vector with 200 m resolution
new_c = interp1(d1,c,new_d); % new depth vector (matched with new_d)

[Alex Hughes]

Thanks for you reply Mathieu. The solution you provide does what I was after. I had a mental block. Indeed all I needed to do was resmample rather than smooth. If you paste your solution in the answers section I'll happily accept it.

[Mathieu NOE]

will do

Answer 1

[Mathieu NOE]

hello

to resample all data to 200 m resolution (whatever your resolution is ), simply use interp1 :

new_d = min(d1):200:max(d1); % new distance vector with 200 m resolution
new_c = interp1(d1,c,new_d); % new depth vector (matched with new_d)