Stupid programming question

Stupid programming question

[Michael French]

    I have two text files each with a single column of numbers in them 
and I want to write a script that multiplies the number on each line of 
file one with the corresponding number from file two and produces a sum 
of the multiplied numbers in the 2 files..  How would I do this with a 
loop?  This is just a small shell script, I can use perl if I need to, I 
just need to know the data structure.  If it was just one file, I would 
do something like this:

SUM=0
NUMBER1=`cat $FILE1`
for m in $NUMBER1
    do
    SUM=`echo "scale=4; $SUM * $m" |bc`
    done

Not exactly right, but you get the jist of it.  Obviously this won't work:

SUM=0
NUMBER1=`cat $FILE1`
NUMBER2=`cat $FILE2`
for m in $NUMBER1 and n in $NUMBER2
    do
    SUM=`echo "scale=4; $m * $n" |bc`
    done

Thanks for any help you can provide, let me know if you need more info.

Michael French

Re: Stupid programming question

[Russell Evans]

On Wed, 19 May 2004 12:06:18 -0500
"Michael French" <mfrench@ashevillemail.com> wrote:

>     I have two text files each with a single column of numbers in them
>     
> and I want to write a script that multiplies the number on each line
> of file one with the corresponding number from file two and produces a
> sum of the multiplied numbers in the 2 files..  How would I do this
> with a loop?  This is just a small shell script, I can use perl if I
> need to, I just need to know the data structure.  If it was just one
> file, I would do something like this:

Putting everything into arrays makes it easy to use the values of the
data and results if you need to do something with them later.

Thank you
Russell

#!/bin/sh

### Variables ###

# First file containing column of numbers
FILE1=/path/file1
# Number of column in first file that contains numbers to be used
COLUMN1=1

# Second file containing column of numbers
FILE2=/path/file2
# Number of column in second file that contains numbers to be used
COLUMN2=1

### Declare Arrays ###
declare -a NUMBER_FILE1
declare -a NUMBER_FILE2
declare -a PRODUCT 

### FUNCTIONS ###
MULTIPLY () { 
 # Pull a column out of two files and multiple
 # Populate arrays with data and result
 # 
 if [ -r $FILE1 ] ; then 
   NUMBER_FILE1=(`awk '{print $COLUMN1}' $FILE1`)
   if [ -r $FILE2 ] ; then
     NUMBER_FILE2=(`awk '{print $COLUMN2}' $FILE2`)
     if [ ${#NUMBER_FILE1[@]} = ${#NUMBER_FILE2[@]} ] ; then
       for (( x=0 ; x<${#NUMBER_FILE1[@]} ; x++ )) ; do
         let PRODUCT[$x]=${NUMBER_FILE1[$x]}*${NUMBER_FILE2[$x]}
       done
     else
       echo "Variance in data structure"
       exit 1
     fi
   else
     echo "$FIL2 is not readable"
   fi
 else
   echo "$FILE1 is not readable"
 fi
} # End MULTIPLY

### MAIN ###
MULTIPLY
echo ${PRODUCT[@]}
for (( y=0 ; y<${#PRODUCT[@]} ; y++ )) ; do
  echo "${NUMBER_FILE1[$y]}*${NUMBER_FILE2[$y]}=${PRODUCT[$y]}"
done 
exit 0

RE: Stupid programming question

[JULIAN, JOHN C (AIT)]

You could read one file into an shell array then do a loop read of the
second file (like in you example) multiplying against the appropriate
array slot.

You could grab a single number from a file with sed.
Count=$( grep -c '$' file1 )
i=1
while read Num1
do 
  Num2=$( sed -n $i file2 )
  Mul=$(( $Num1 * $Num2 ))
  ...
  i=$(( i + 1 ))
done < file1

You can use $Count to check if you've gone beyond the end of file2.

John Julian


-----Original Message-----
From: linux-admin-owner@vger.kernel.org
[mailto:linux-admin-owner@vger.kernel.org] On Behalf Of Michael French
Sent: Wednesday, May 19, 2004 1:06 PM
To: linux-admin@vger.kernel.org
Subject: Stupid programming question


    I have two text files each with a single column of numbers in them 
and I want to write a script that multiplies the number on each line of 
file one with the corresponding number from file two and produces a sum 
of the multiplied numbers in the 2 files..  How would I do this with a 
loop?  This is just a small shell script, I can use perl if I need to, I

just need to know the data structure.  If it was just one file, I would 
do something like this:

SUM=0
NUMBER1=`cat $FILE1`
for m in $NUMBER1
    do
    SUM=`echo "scale=4; $SUM * $m" |bc`
    done

Not exactly right, but you get the jist of it.  Obviously this won't
work:

SUM=0
NUMBER1=`cat $FILE1`
NUMBER2=`cat $FILE2`
for m in $NUMBER1 and n in $NUMBER2
    do
    SUM=`echo "scale=4; $m * $n" |bc`
    done

Thanks for any help you can provide, let me know if you need more info.

Michael French
-
To unsubscribe from this list: send the line "unsubscribe linux-admin"
in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: Stupid programming question

[A. R. Vener]

#!/usr/bin/perl

open(FILE1, "file1") or die  "cannot open file 1\n";
open(FILE2, "file2") or die  "cannot open file 2\n";

while ($n1 = <FILE1>  and $n2 = <FILE2>)
{
chomp $n1;
chomp $n2;
$product = $n1 * $n2;
print "$product\n";
}
}


--
Rudy