Create multiple files with a loop

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Create multiple files with a loop

Posted on 2008-02-18 08:28 By Karl-Ranz (9)

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How do I ...? with Maple

Good morning everyone

I have a question concerning Maple file output. Is there a way, that I can produce multiple files with Maple using a loop? My main problem is how to get Maple to create files with different names, like file1.txt -> file2.txt -> file3.txt ..... because so far i figured, that

fopen("file[i].txt",WRITE) , with i beeing the loop index

does not work :)

Thank you for any help

Karl

string

Comment on 2008-02-18 09:31 from Axel Vogt ( Maple Rating 4

948)

in that case try to concatenate "file" + convert(i,string) + ".txt" to get a string as name

sprintf instead of catenation

Comment on 2008-02-18 11:34 from Joe Riel ( Maple Rating 4

1248)

The + sign doesn't catenate strings in maple, though possibly you weren't suggesting that. The cat function does. However, I prefer sprintf here:

for i to 3 do

  fopen(sprintf("file%d.txt", i),'WRITE');

end do;

Using sprintf

Comment on 2008-02-18 11:30 from John Fredsted ( Maple Rating 4

566)

You could also write sprintf("file%d.txt",1), etc.

pointless

Comment on 2008-02-18 11:42 from Joe Riel ( Maple Rating 4

1248)

Hi John,

Your typing was quicker than mine, but I cleverly replied to the immediate poster rather than the original, so my response appears before yours. We can split the single point. Congrats on winning the MaplePrime award, that wasn't a surprise.

It's Louis Riel day in Manitoba, so I'll be celebrating, even if I'm not there...

Smiling

Comment on 2008-02-18 12:01 from John Fredsted ( Maple Rating 4

566)

Hi Joe,

It made me smile seeing that our posts had crossed each other. I guess I came before you, in time that is, because I typed less letters than you did.

Thanks for your words concerning the award. I had a maplesoft mug shipped (or rather flown, I reckon) all the way from Canada to the little kingdom of Denmark, in the flimsy hope that having coffee contained in a mug with the maplesoft name and logo on would somehow rub off on my performance when working with Maple and when attending this forum. The jury is still out on that issue; a little more data sampling is required. Obviously, it did not help this morning, compare the post Sleepy me.

What is Louis Riel day in Manitoba? Manitoba makes me think of a song by the Scottish band Runrig. Do you know them? They have a song referring to Manitoba. Cannot remember the title of that song, though.

Riel

Comment on 2008-02-18 12:16 from Joe Riel ( Maple Rating 4

1248)

Louis Riel was a significant figure in Canadian history (not to mention my own family history). He led the Metis, a blend of native and French settlers, in a revolute against the Canadian government. He was one of the founders of the Manitoba province. Eventually met his fate at the end of a rope (a few hours before I was born, modulo the year). The province of Manitoba, last year, designated this day (not historically relevant, but a holiday throughout Canada) as Louis Riel day.

History

Comment on 2008-02-18 12:36 from John Fredsted ( Maple Rating 4

566)

Thanks for those fascinating historical facts. The title of the song by Runrig is Rocket To The Moon.

Strings, yes sounds good

Comment on 2008-02-18 17:20 from Karl-Ranz (9)

Hi Axel, Joe and John

thanks for the quick help. I didn't figure in the beginning that adding a plain converted i to string entry could help, but now it sounds reasonable.

Well, congratulations to MaplePrime award and have a nice evening

Karl

File Handles

Comment on 2008-02-18 17:57 from Joe Riel ( Maple Rating 4

1248)

A practical point that we overlooked is accessing these files. The call to fopen returns a file handle (a posint) that can be used for later reference, rather than the filename. Thus,

for i to 3 do

  fd[i] := fopen(sprintf("file%d.txt", i), 'WRITE');

end do:

Then you could do

for i to 3 do

    fprintf(fd[i], "Writing to file %d\n", i);

end do;

When finished,

fclose(seq(fd[i], i=1..3));

How about using cat?

Comment on 2008-02-18 20:30 from jaytreiman (

41)

Can you generate the names using cat?

cat("file",i,".txt");

cat, with range

Comment on 2008-02-18 20:37 from Joe Riel ( Maple Rating 4

1248)

That works as well. In fact, you could do the following to create a list of the files names:

files := [cat]("file", 1..3, ".txt");   
               files := ["file1.txt", "file2.txt", "file3.txt"]

}

Create multiple files with a loop

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