Find and replace in fortran

Question

Find and replace in fortran

galaxytraveler (Aerospace)

(OP)

14 Mar 12 12:15

How to do find and replace in Fortran or ideas for a different way of solving the problem

BACKGROUND
I am reading in a column of asteroid diameters from a file, some of the asteroids are however not spherical but can be e.g. potato shaped, and then instead of a diameter I get something like "250x23x75.5" or if just two sides are known I get something like "250x23".

What I need to do with these values are to take the non-spherical ones and calculate the diameter of a sphere with equal volume.

THE PROBLEM
My problem is that I don't know how to take a value like "diameter = 250x23x75.5" and get the individual numbers out so I can calculate anything.

MY OWN IDEAS
I have been considering doing an "find and replace" of all the x to *, so I can directly use it in the calculations. But I am not sure how to do "find and replace", or if I will have problems using a string in a formula. And then how I can be sure to insert "250x23" into a different formula than "250x23x75.5".

For the find and replace I have considered turning each value into an array, so e.g. "250x23" would be the array (2,5,0,x,2,3) and then running a if loop on it, to search for X's and replace them. But I am not sure how to do this either, and it seems like a complicated way of doing something so simple.

I hope someone are willing to give me some new ideas.

Denial (Structural) · Answer 1 · 2012-03-14 16:19:23

I have not used FORTRAN for many years now, but isn't this the sort of thing that the CHARACTER*1 variable type was introduced for. Read the data as a CHARACTER string, then search that string for whatever signposts you are looking for. When you need to extract the numbers from the substrings between the signposts, use an "internal read".

IDS (Civil/Environmental) · Answer 2 · 2012-03-14 18:29:02

It probably can be done in Fortran, but it looks like something that would be much more easily done in a spreadsheet to me.

Doug Jenkins
Interactive Design Services
http://newtonexcelbach.wordpress.com/

gsal (Computer) · Answer 3 · 2012-03-14 21:18:15

Sure, it can be done...you just need to be patient and get creative.

For example, you read the info as a string and then you inspect it to find out how many 'X' it has and at what index they are at...then you do an internal read of the characters in between.

Or, you could take a look at the modules put together in this page:
http://www.gbenthien.net/strings/index.html

Or, you could use something else other than fortran that has a lot more abilities on manipulating strings and spliting, etc, ...like, say, Python.

xwb (Computer) · Answer 4 · 2012-03-17 07:35:48

You just need a parser. Example attached. I'll leave you to do the file opening etc.

http://files.engineering.com/getfile.aspx?folder=e3b8c44f-48b3-42a8-b80b-4d

galaxytraveler (Aerospace) · Answer 5 · 2012-03-20 13:09:56

Thanks you so much for all your answers, I really appreciate that you used your time on answering me.

IDS: I took data into excel and it was much easier than Fortran, and I got some plots out after some manipulating, but my input file will get renewed often, so in the long run, it is better for me to do as much to in Fortran as possible.

Denial and gsal:Thanks for pointing me towards "internal read" and charecter*1 variables. (The reason why I am using Fortran is my boss wants me to build on his old programs to save time).

Xwb- You wrote a script for me, WOW!!! Thanks! I am going through it now, to understand it and make it fit in my program.

loki3000 (Mechanical) · Answer 6 · 2012-04-10 05:59:24

if it's possible, use python as a glue language and call your fortran routines from it

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Find and replace in fortran