Processing a Data Structure

[Iris83]

Hi,

I have a question about converting some of the data in my dataset but leave some data the way it is.

I have a hash and if the key is present and the Value of the Hash equals B it should convert these number but if B is not present the data should remain the same.

my output is that all the data is converted not in the only the cases were B is present.

This is the script i have

while ($data = <Dataset>) {
	if (exists $hash[1]) {
		if ($hash[2]==B) {
			for ($i = 0; $i < length($data); $i++) {
				$characterString = substr($data, $i, 1);
				$newCode = $characterString;
				if ($characterString eq "1") {
					$newCode = "0";
				}
				if ($characterString eq "0") {
					$newCode = "1";
				}
				if ($characterString eq "2") {
					$newCode = "3";
				}
				if ($characterString eq "3") {
					$newCode = "2";
				}
				substr($data, $i, 1) = $newCode;
			}
			print "$data\n";
		}
		else {
			print $data\n";
		}

I hope someone can help me with this.

[KevinADC]

Do you have an array or a hash?

if (exists $hash[1]) {

$hash[1] is an array index, not a hash key. Hash keys use curly brackets {}

if (exists $hash{1}) {

[KevinADC]

'B' is a string (most likely) not a number, so use 'eq' instead of '==':

$hash[2] eq 'B'

[Iris83]

Thank you for your help. I tried it like you said it is a hash so this is what i used but im not getting any output! I hope you can help me figure out what i should do!

while ($data = <Dataset>) {
	if (exists $hash{1]} {
		if ($hash{2} eq 'B') {
			for ($i = 0; $i < length($data); $i++) {
				$characterString = substr($data, $i, 1);
				$newCode = $characterString;
				if ($characterString eq "1") {
					$newCode = "0";
				}
				if ($characterString eq "0") {
					$newCode = "1";
				}
				if ($characterString eq "2") {
					$newCode = "3";
				}
				if ($characterString eq "3") {
					$newCode = "2";
				}
				substr($data, $i, 1) = $newCode;
			}
			print "$data\n";
		}
		else {
			print $data\n";
		}

[Iris83]

Accessing The keys and values in a Hash

Hi i want to use the keys and values of a hash to compare them with other files. But i can't acces them.

This is my code i hope somone can help!

my %hash;

while( <Data> ) {
	@elements = split /,/, $_;

	if( $elements[1] ne '' ) {
		$hash{ $elements[1] } = $elements[2];
	}
}

while ($data = <Dataset>) {
	if (exists $hash{1}) {
		if ($hash{2} eq 'B')
			print $data;
		else {
			print $data;
		}
	}
}

[docsnyder]

@Iris83

I'm not quite sure what you are intending to do.

$hash{ $elements[1] } = $elements[2];

Do you really mean the second and the third element? Remember, the first array element has index 0.

You are accessing $hash{1} and $hash{2}. Are 1 and 2 really the hash keys you mean?

if ($hash{2} eq 'B')
print $data;
else {print $data;
}

Why an if-statement when printing data in any case?

Please, can you give a short example of what your input files consist of?

Greetz, Doc

[KevinADC]

check you code for proper syntax:

{1]

should be:

{1}

[Iris83]

The syntax is indeed {1} in my script but it doesn't work!

so any tips would be appreciated!

[KevinADC]

need to see some of the data you are working with.

[Iris83]

I have 2 datasets one containing data like this

11,1,B
12,2,B
13,3,T
21,4,T
22,5,T

From this data i want the 2nd row to be the keys in the hash and the 3th row the values.

my 2nd data set looks like this

1 1 1 0 0
2 1 0 1 1
3 1 0 1 1
5 1 0 0 0

for example if the first key which is 1 exists and the value is B i want to reverse the data from 1 to 0 and 0 in 1. If the key is present and the value is T it should just print the normal data.

I was told that you could acces the hash keys like this $hash{1} and the values like this $hash{2} .

I hope this clarifies thing and you are able to help me with my problem.

my %hash;

while( <Data> ) {
	@elements = split /,/, $_;

	if( $elements[1] ne '' ) {
		$hash{ $elements[1] } = $elements[2];
	}
}

while ($data = <Dataset>) {
	if (exists $hash{1}) {
		if ($hash{2} eq 'B') {

for ($i = 0; $i < length($data); $i++) {
                $characterString = substr($data, $i, 1);
                $newCode = $characterString;
                if ($characterString eq "0") {
                        $newCode = "1";
                }
                if ($characterString eq "1") {
                        $newCode = "0";
                        }
               
                substr($data, $i, 1) = $newCode;
			print $data;
		else {
			print $data;
		}
	}
}
}
}

[miller]

substr($data, $i, 1) = $newCode;
			print $data;
		else {
			print $data;
		}

Your above code doesn't even compile. There is a floating else in the above section.

- M

[miller]

Iris83,

These are the exact same problem. I'm merging the threads to keep us from duplicating effort and comments.

- M

[KevinADC]

I think this is what you are trying to do:

while( <Data> ) {
   chomp;
   my @d = split /,/, $_;
   if( $d[1] ne '' ) {
      $hash{ $d[1] } = $d[2];
   }
}

while (my $data = <Dataset>) {
   chomp $data;
   my @e = split /\s+/, $data;  
   if ($hash{$e[0]} eq 'B') {
      foreach my $i (1..$#e) {
         $e[$i] =~ tr/10/01/;
      }
   }
   my $d = join(' ',@e);
   print $d,"\n";
}

it could probably be done many different ways.

[miller]

I was told that you could acces the hash keys like this $hash{1} and the values like this $hash{2} .

That is not correct. You find out the basic information concerning hashes in the flowing perldoc link about perl varaible types:

http://perldoc.perl.org/perlintro.html#Perl-variable-types

Finally, Kevin's code is likely what you're looking for, but you should do some more reading if you expect to be able to debug it in the future.

- M