awk 跳过记录。 获取线命令

Question

this is a task related to data compression using fibonacci binary representation.

what i have is this text file:

result.txt

a 20
b 18
c 18
d 15
e 7

this file is a result of scanning a text file and counting the appearances of each char on the file using awk.

now i need to give each char its fibonacci-binary representation length. since i'm new to ubuntu and teminal, i've done a program in java that receives a number and prints all the fibonacci codewords length up to the number and it's working. this is exactly what i'm trying to do here. the problem is that it doesn't work... the length of fibonacci codewords is also work as fibonnaci. these are the rules:

• f(1)=1 - there is 1 codeword of length 1.
• f(2)=1 - there is 1 codeword of length 2.
• f(3)=2 - there is 2 codeword of length 3.
• f(4)=3 - there is 3 codeword of length 4.

and so on... (i'm adding on more bit to each codeword so the first two lengths will be 2 and 3)

this is the code i've made: its name is scr5

{
a=1;
b=1;
len=2

print  $1 , $2, len;
getline;
print   $1 ,$2, len+1;
getline;
len=4;

for(i=1; i< num; i++){
    c= a+b;
    g=c;
    while (c >= 1){
        print $1 ,$2, len ;
        if (getline<=0){
            print "EOF"
            exit;
        }
        c--;
        i++;
    }
    a=b;
    b=c;
    len++;
}}

now i write on terminal:

n=5
awk -v num=$n -f scr5 a

and there are two problems: 1. it skips the third letter c. 2. on the forth letter d, it prints the length of the first letter, 2, instead of length 3.

i guess that there is a problem in the getline command.

thank u very much!

Answer 1

Search Google for getline and awk and you'll mostly find reasons to avoid getline completely! Often it's a sign you're not really doing things the "awk" way. Find an awk tutorial and work through the basics and I'm sure you'll see quickly why your attempt using getlines is not getting you off in the right direction.

In the script below, the BEGIN block is run once at the beginning before any input is read, and then the next block is automatically run once for each line of input --- without any need for getline.

Good luck!

$ cat fib.awk
BEGIN { prior_count = 0; count = 1; len = 1; remaining = count; }

{ 
    if (remaining == 0) {
        temp = count;
        count += prior_count;
        prior_count  = temp;
        remaining = count;
        ++len;
    }

    print $1, $2, len;
    --remaining;
}

$ cat fib.txt
a 20
b 18
c 18
d 15
e 7
f 0
g 0
h 0
i 0
j 0
k 0
l 0
m 0

$ awk -f fib.awk fib.txt
a 20 1
b 18 2
c 18 3
d 15 3
e 7 4
f 0 4
g 0 4
h 0 5
i 0 5
j 0 5
k 0 5
l 0 5
m 0 6

Answer 2

The above solution, compressed form :

mawk 'BEGIN{ ___= __=  _^=____=+_  }  !_ { __+=(\
            ____=___+_*(_=___+=____))^!_ } $++NF = (_--<_)+__' fib.txt

a 20 1
b 18 2
c 18 3
d 15 3
e 7 4
f 0 4
g 0 4
h 0 5
i 0 5
j 0 5
k 0 5
l 0 5
m 0 6