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How to read from and write to a table in a file (CSV)? [message #10323]

Mon, 02 July 2007 09:50

$$mike{is_here} is currently offline$ $mike{is_here}
Messages: 12
Registered: July 2007

Promising Member

Hi,

I'm new to Ultimate (which I like very much) and look for a concept idea, i.e. which elements are most suited to use.

Suppose, I have a CSV table like this:

A,B,C
1,2,3
4,5,6

Reading it line-by-line is no problem. E.g. I can store each line as a String or (already decomposed) in a Vector<String> or Vector<Value>. Once I read the table from the file I'm interested in the columns. E.g. I'd like to get column C for further manipulation:

C, 3, 6

Suppose I changed it into somethig different, like:

D,100,200

I want to assemble a new table for storage, e.g.

D,B,C
100,2,3
200,5,6

I'm not aware that there is something ready-to-use for this purpose, besides ArrayCtrl, may be.

Thank you for your help.

Kind regards, Micha

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Re: How to read from and write to a table in a file (CSV)? [message #10325 is a reply to message #10323]

Mon, 02 July 2007 09:58

mirek
Messages: 14258
Registered: November 2005

Ultimate Member

You need to handcode.

Some quick tips for parsing / storing:

Stream::GetLine

CParser

Split

Vector< Vector<String> >

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Re: How to read from and write to a table in a file (CSV)? [message #10339 is a reply to message #10325]

Tue, 03 July 2007 09:23

$$mike{is_here} is currently offline$ $mike{is_here}
Messages: 12
Registered: July 2007

Promising Member

Hi Mirek,

Thanks, I used most of your ideas.

Dear all,

Because this post seems to catch some interest please find attached my solution (XP's zip). The functions

String 		cleanup(String s);
Vector<String>	getLines(String s);
String 		load(char* filename);
bool 		save(const char *filename, const String& data);
String 		ToString(const Vector<String>& vs);
Vector<String>	transpose(const Vector<String>& vs);

help to convert input.txt

 A,	B  , 	 C		,D	
1,10  ,   100,	5
		2,20 , 200,55

into output.txt

A,1,2
B,10,20
C,100,200
D,5,55

Any suggestion, feedback or comments are welcome. This code so far does just the required minimum. I.e. it will fail when the number of elements vary. I wonder how to take care of such issues, e.g. through throwing exceptions (try, catch) or else?

What would you do?

Kind regards,
Micha