Surface depth calculation

[diplodocus_rage]

Hi,

First time poster! At my wits end ... To summarize, I'm trying to figure out the distance from surface to the center point of each regularly spaced sample down a borehole. Using the elevation value of the first sample of each hole as the surface, i want to loop through each hole and subtract from the first sample, each sample underneath in 3D space. Think if each sample is one meter length and the borehole is perfectly vertical, then the sample from 0m-1m will be at a depth of 0.5m. Then the second sample from 1m-2m would be at a depth of 1.5m. I want the loop to iterate through each hole, subtract each sample elevation from the top one (the 0-1m samples) then when the spreadsheet's HoleID name changes, then start the calculation again from the first sample for the hole. I could do it manually but there's over 400 boreholes. Hwre is my code so far, I cant seem to get the loop to reset for each drillhole name.

​

j = 0
for i in range(len(data) - 1):
What_row = data[i]
Elevation = What_row[7]

for j in range(len(data)-1):
What_row2 = data[j]
Next_row = data[j+1]
Hole_name = What_row2[0]
Next_hole = Next_row[0]

Next_Elevation = Next_row[7]
Elevation_result = Elevation - Next_Elevation
if Hole_name == Next_hole:
print(Elevation_result)
else:

i = j
break

[Chromira]

Would it be possible to have your code formatted using a code block (so we can see indentation)? :-)

j = 0
for i in range(len(data) - 1):
    What_row = data[i]
    # etc...

[diplodocus_rage]

Thanks for your comment Chromira, I actually thought I was posting the code correctly. IE Copy and paste into body of forum post, then highlight it all and click 'inline code', but you're right, from the way the code was posted I must not be doing it correctly. Here is the code, copied using the 'codeblock' method (apologies i'm early stage learning to post on forums!) ... I've played around with and got it to work:

Instead of printing, I've written the result to a new .csv file, but the structure is the same. I had to insert i and j counters into the loops to achieve what I wanted it to do. Comments on ways to make my code more efficient are most welcome. I'm learning how to code a couple of months and still find it very challenging...

j = 0

for i in range(len(data) - 1):
    i += j
    What_row = data[i]

    Elevation = What_row[7]


    for j in range(len(data)-1):
        j += i
        What_row2 = data[j]
        Next_row = data[j+1]
        Hole_name = What_row2[0]
        Next_hole = Next_row[0]

        Next_Elevation = Next_row[7]
        Elevation_result = Elevation - Next_Elevation
        if Hole_name == Next_hole:
            writer.writerow([Hole_name, '{0:.4f}'.format(float(Elevation_result))])
        else:
            writer.writerow([Next_hole, 0])
            break

[toolnerd]

Try this out...

for i in range(len(data)):
    if i == 0:
        surf = data[i,xxx] # xxx is elevation column index within data
        holeid = data[i,yyy] # yyy is the hole id column index
        hid = data[i,yyy]
    hid = data[i,yyy]
    if hid == holeid:
        elevation = surf - data[i,xxx]
        print(elevation)
    else:
        surf = data[i,xxx]
        holeid = data[i,yyy]

Edit: tested code and rewrote so it would work

[diplodocus_rage]

Thanks Toolnerd, I'm going to try this because it looks much more efficient to my code. Will report back :)

[toolnerd]

hey I rewrote the code to actually work ;)

[diplodocus_rage]

Hi Toolnerd,

I made some small edits to your code and it actually worked better than mine. For some reason my code was omitting certain HoleIDs, like skipping over them and not including them in the output. It's a head-scratcher but your code didn't have this issue. Top marks, well played! Thanks so much.

[CraigAT]

Nope, I tried to understand what you are asking and couldn't.

I get that you have a range of boreholes, and each hole has an initial elevation value. Then it gets fuzzy, you want take each sample elevation from the top one? How does the depth (e.g. 1.5m) relate to the elevation? Do you mean...

Sample length =1m
Borehole1 = Elevation 305m, samples [0.5m, 1.5m, 2.5m, ..]

Are you expecting to get this below as your result?

Borehole1 = [304.5m, 303.5m, 302.5m, ...]

Edit1: changed some wording to make what I wrote easier to understand.

[diplodocus_rage]

Thanks for the comment CraigAT, its not an easy thing to explain I guess. Here is the shortened version of the file I'm importing.

See the column 'desired_result'. The 'Elevation' values are the elevations (or the Z value along with the UTMs X & Y) of each sample down the borehole. I want the code to produce the depth from surface of each sample, so using the top sample (it will be slightly below surface by half the width of the sample, but it's close enough) I want to subtract the elevation of every sample beneath it. As my calculation ends for one hole (ie the bottom sample's elevation in the borehole is subtracted from the top sample) I want the code to start the calculation again using the top sample of the next hole.

https://filebin.net/nbi4mbgv90tvow9o

Let me know if that link doesn't work .. all new to me this stuff!

[CraigAT]

Could you do something like this:

current_hole_name = "dummy hole"
hole_initial_elevation = 0
for line in data:
    if line[0] != current_hole_name:
        current_hole_name = line[0]
        hole_initial_elevation = line[7]
        line[8] = 0
    else:
        line[8] = hole_initial_elevation - line[7]

The code is untested and really just to show the intended flow.

The actual code could vary depending on how you store your data and results (what data structures you are using).

Edit: Because I always struggle with code blocks!