Shell Programming and Scripting

okay so my job is requiring me to learn perl and i have never had any type of programming language... ever.

So i need to take a file that has data (nodes/points) with x, y, and z components.

Example of what the file contains is below:

Code:

RANDOM TEXT
RANDOM TEXT
Node #          x pos              ypos          zpos
5948             50.24              125.35          5.79
(there are over 200 lines of this data)
RANDOM TEXT
RANDOM TEXT

i need to somehow open this file, grab the data for Node, x position, y pos, and z pos and from this data be able to calculate which node is closest to a given position by a user defined input.

so if the user enters a position of lets say 10 for the x pos, 10 for the y pos, and 10 for the z pos. (just keeping it simple) the code needs to be able to loop through the data and find the node with the closest corresponding positions.

ANY help is much appreciated!!

Few questions:

1. Please post few lines from the input file spanning few lines from random text, few lines of node data, and few more lines of random text. The simplest way to loop through the nodes and positions is by checking if the line starts with a number (unless no other random text starts with a number too)

2. When you say grab the closest point, do you mean the point from file nearest to the user inputted data:
dist = sqrt ((x_input - x)^2 + (y_input - y)^2 + (z_input - z)^2)

I dont have the file with me right now but yes, it contains other sets of numbers (which i don't need) along with other information that was gathered from a simulation.

and when i say grab the closest point (node), i mean that i want to find a node that is closest to a user inputted position. So if the user inputs values for x,y,z as 10,10,10 and my data set only contains 2 nodes with positions 11,11,11 and 50,50,50 i want it to tell me that the node with the 11,11,11 position is closest to the user inputted position of 10,10,10

It'd be helpful if you can post sample input data.

And, I'm sure the co-ordinates are not as simple as (11,11,11) and (12,12,12).

If user inputs (10,10,10) and the file contains (9,10,11) and (11,9,10), then which point will you choose? (If you plot these points on a graph and measure the distance between (10,10,10) from the other two points, it'd measure the same.)

What logic are you following to determine the closest point?

I will reply tomorrow with the file and code im using. it will make it a little easier to explain

---------- Post updated at 07:59 AM ---------- Previous update was at 12:52 AM ----------

Code:

open (FILENAME, "<FILEPATH")

but i guess to start off im not exactly sure how to only gather the first set of data from the file and nothing else.

That answers the first question. Second question is how would you want to find the nearest node given the input co-ordinates?

From my understanding, this looks like the Finite Element Analysis of a bar. And you might want to use the distance formula (mentioned in post #2) to determine the nearest node.

To open a file, you can use this: open FH, "< /path/to/file";
Use this filehandle 'FH' in a loop to read each line of file.

You are correct about the FEA. My current code looks as followed: (all it dose is output the entire file from above post into my command screen)

Code:

use feature ':5.10';
use warnings;
use strict;


#print "Enter File Path:\n"

#$file_path = <>;
my $LINE_VAR; 

open (COORD, "</projects/student2/Projects/FEA_AN/GM_Back_structure/Tensile_Bar_TEST.inp");

while (<COORD>) {

    my @raw_data = <COORD>;

        foreach $LINE_VAR (@raw_data)
{


            print "$LINE_VAR";

}

}
close (COORD);

And i guess the distance formula would work if it allows me to input a position, and from there it calculates the closest node.