Basically I am trying to calculate the result of "the path" in $3 where the operators follow the number and not preceding them like we normally do:
rec_10: +1+2-2=1
But I realise (I am sure there is a good reason for that) that awk does handle basic arithmetic operations, like:
(+1) + (2) + (-2) = 1
Giving that to awk:
Code:
awk '{a==1; b==2; c==(-2); print a+b+c}'
makes it stuck in a loop.
Therefore, I think the approach of putting the numbers and operators in the right order (code below) would not work at the end anyway:
I have no idea what you are trying to do. Arithmetic operators (except unary minus) work on two operands. Therefore, a arithmetic formula has one more operand than there are operators. But, your example has 3 operands and 3 operators.
Are you saying that you want each number to have a trailing + or - sign to indicate whether the number is positive or negative and you then want to add up all of the signed numbers?
gawk: (FILENAME=- FNR=1) fatal: function `x' not defined
I am having trouble following the logic of your script.
The diagnostic you are getting is because the sequence x(i) is a request to call the function named x with the parameter i, you haven't defined any functions, and the function x is not one that is defined by gawk. Furthermore, you can't have a variable and a function with the same name.
Note that the statement: x==0; is a logical expression (not an assignment statement) returning the value 1 if the variable x is zero or an empty string; otherwise it returns 0. (Note that the value of that logical expression doesn't affect the behavior of this script in any way; it does not assign a value to x.)
Although the gawk statement:
Code:
a=split($2,b,"");
splits the 2nd input field into the array b[] with each element of b[] being set to one character from that field and sets a to the number of characters found; using an empty string as an ERE specifying the field delimiter is not available in all versions of awk (including the one I am using on OS X).
You might want to try something more like:
Code:
awk '
BEGIN { FS = OFS = "|" # Set input and output field separators.
}
{ # Initialize the accumulated sum and the current input number to zero.
sum = number = 0
print "Processing input: " $2
end = length($2)
# Process each character in the 2nd field from left to right...
for(i = 1; i <= end; i++) {
if((c = substr($2, i, 1)) ~ /[0-9]/)
# We found a digit, add it to the current number.
number = number * 10 + c
else { # If it is not a digit it must be a + or -...
if(c == "+")
# We found a +, add number to sum.
sum += number
else
# Assume we found a minus sign; subtract number
# from sum.
sum -= number
# We are now ready to look for the next number.
number = 0
}
}
# Print the results...
print $1, sum
}' file
This is a nice approach, and works fine with gawk and other awk implementations that use FS="" to split each input character into a field. A similar approach that doesn't depend on this behavior (which the standards say produces unspecified results) would be:
which also has a little feature creep allowing a decimal point to be included in the input numbers (sparked by RudiC's code using %f instead of %d in the sprintf() format string).
If you change:
Code:
gsub (/[0-9]*/, _, $2)
in RudiC's script to:
Code:
gsub (/[0-9.]*/, _, $2)
his script will also handle floating point values in awk versions where:
Code:
split ($2, S, "")
doesn't produce a syntax error.
This User Gave Thanks to Don Cragun For This Post:
The problem reminds me of a rudimentary RPN calculator that I recently did. As it expects operands and operators in separate fields, I added a gsub with spaces at the begin of each step:
Code:
awk '
function CALC(X, Y) {if (OP == 1) return X + Y
if (OP == 2) return X - Y
if (OP == 3) return X * Y
if (OP == 4) return X / Y
}
{gsub (/[|+-]/, " & ")
for (i=2; i<=NF; i++) {OP = index ("+-*/", $i)
if (OP) STK[--PNT] = CALC(STK[PNT], STK[PNT+1])
else STK[++PNT] = $i
}
if (PNT == 1) print $1 "|" STK[PNT]
else print "invalid"
PNT = 0
}
' file
rec_10|1
rec_20|10
rec_30|911
rec_40|-911
( and, in principle, it would need a 0 operand in the beginning. It uses the "|" now resulting in a zero value to start with)
I have to do some arithmetic operation on Field 8 which is calculated by Field 9/Field 7
Suppose i have data like :
0800123456|JAN|2017|JAN|2018|0800123456|0|0.0000|0.00|
0800234567|JAN|2017|JAN|2018|0800234567|4|2.5812|10.32|
0800666666|JAN|2017|JAN|2018|0800666666|2|1.7255|3.45|... (0 Replies)
Hi,
Here is the script i try to perform arithmetic operation in two variables .
git branch -r | while read brname ; do
REV_COMMITS=`git rev-list --count $brname`
echo "$brname has $REV_COMMITS"
(( TOTAL = TOTAL + REV_COMMITS ))
echo "in loop" $TOTAL
done
echo "total is " $TOTAL
... (3 Replies)
I am writing a script in zsh shell, it fetchs a number from a file using the awk command, store it as a variable, which in my case is a small number 0.62000. I want to change this number by multiplying it by 1000 to become 620.0 using the command in the script
var2=$((var1*1000))
trouble is... (2 Replies)
Hi
I have a file with 3 columns. say,
infile:
1 50 68
34 3 23
23 4 56
-------
-------
I want to generate n files from this file using a loop so that 1st column in output file is (column1 of infile/(2*n+2.561))
I am doing like this:
for ((i=1; i<=3; i++))
do
a=`echo... (3 Replies)
Hi all,
I would appreciate if anyone knows how to perform adding to date.
As for normal date, i can easily plus with any number.
But when it comes to month end say for example 28 Jun, i need to perform a plus with number 3, it will not return 1 Jul.
Thanks in advance for your help. (4 Replies)
Hi, All,
I have a file, its content is as follows:
100 150
120 135
140 170
I want to insert a column, its content is determined by the difference between the two values in the same line, if the difference is less than 20, the new value is 1, otherwise is 0.
after the operation, the... (1 Reply)
I am using egrep to extract numbers from a file and storing them as variables in a script. But I am not able to do any arithmetic operations on the variables using "expr" because it stores them as char and not integers. Here is my code and the error I get. Any help will be appreciated.
#!/bin/sh... (3 Replies)
I have no idea why I can't get this to work, if anybody can help i would appreciate it.
#!/bin/bash
x=`cat counter.txt | wc -l`
y= '$x / 7'
printf "%d People have visited this page" $y
:confused: (2 Replies)
12-19-2015
