Python, interpolation,

Question 1

This issue realy drives me crazy. I have got ascii file with ~1 000 000 rows in it. There are 3 columnsX - coordinate, Z- depths- V -speed. For instance:

         X            Z               V      45000       -11657.8        5985.61      45000      -11578.22       5974.688      45000      -11259.92       5930.935     287800      -1034.451       2062.341     287800      -1014.557       2051.226     287800      -934.9814       2006.724

I need interpolate Depth(Z)[-15 000 to 0] with Speed(V) by steps (For each 2000m or 100m etc)For example

       45000       -11657.8        5985.61       45000       -11600          ??????       45000       -11578.22       5974.688       45000       -11500          ?????       45000       -111034.451     2062.341       287800      -934.9814       2006.724       287800      -900            ????       287800      -895.1937       1984.451

What I did:

import numpy as npfrom scipy.interpolate import interp1dwith open('my data' ,'r') as f:header1 = f.readline()  ###skip the first head line  X_list=[] #### Create 3 empty listsZ_list=[]V_list=[]for line in f:    line = line.strip()    columns = line.split()    X = (float(columns[0])) ### separete columns and add to list and convert     Z = (float(columns[1])) ###to float    V = (float(columns[2]))    X_list.append(X)    Z_list.append(Z)    V_list.append(V)x = np.linspace(min(Z_list),max(Z_list),6) ## step 3000m = 6 partsprint (x)

result:

[-15000. -12000. -9000. -6000. -3000. 0.]

Now I got:

X             Z         V45000       -15000    ??????45000       -12000    ??????45000       -9000     ??????45000       -6000     ??????45000       -3000     ??????

So the question is. How could I interpolate this speed to interesting depths for each coordinates??Thank you for any advice

Question 2

Where are you actually applyinginterp1d and what's going wrong, exactly?

Question 3

I didn't set 'x' I wrote np.interp(X_list,x,V_list)

Question 4

In order to interpolate, you need some example of inputs and outputs that will be the base of the interpolation. In your case,Z_list is the input andV_list, the output.

Next, you can use theinterp function fromnumpy, which expect an array to interpolatex, followed by the inputZ_list and outputV_list. Let's follow the example inits documentation.

import numpy as npprint np.interp(x, Z_list, V_list)

Question 5

That realy wokrs! Thank you! I tried it before, but instead ''x'' I put X_list - becouse I thought the first parametr need to be a coordinate

Matheus Portela 2,4701 gold badge23 silver badges32 bronze badges · Accepted Answer · 2016-09-08 17:14:30Z

In order to interpolate, you need some example of inputs and outputs that will be the base of the interpolation. In your case,Z_list is the input andV_list, the output.

Next, you can use theinterp function fromnumpy, which expect an array to interpolatex, followed by the inputZ_list and outputV_list. Let's follow the example inits documentation.

import numpy as npprint np.interp(x, Z_list, V_list)

That realy wokrs! Thank you! I tried it before, but instead ''x'' I put X_list - becouse I thought the first parametr need to be a coordinate

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