You've got some serious quoting issues.
This should provide you with an example. Prints 'x' if the value in column 1 of the input is not 1, 2 or 3, otherwise translates it.
Code:
awk '
BEGIN {
a["1"]="a";
a["2"]="b";
a["3"]="c";
}
{ print !( $1 in a) ? "x" : a[$1]; }
'
Your code works if the record contains only 1 letter.
But what if it contains a string of letters instead.
How do I make the difference between the end of the string and an unknown number?
input:
Code:
1233
33
243
11792
output:
Code:
abcc
cc
bXc
aaxxb
Last edited by beca123456; 09-18-2012 at 11:04 PM..
awk '
BEGIN {
xtab["1"]="a";
xtab["2"]="b";
xtab["3"]="c";
}
function xlate( w, xw, i, n, a ) # translate all characters in w using xtab returning the translation
{
xw = "";
n = split( w, a, "" );
for( i = 1; i <= n; i++ )
xw = xw (a[i] in xtab ? xtab[a[i]] : "x");
return xw;
}
{ print xlate( $1 ) }
'
You are getting the extra X at the end because you are executing your loop one time more than you have pairs in your string. This is the way I would have coded it:
Code:
awk '
BEGIN {
xtab["11"]="a";
xtab["12"]="b";
xtab["13"]="c";
}
function xlate( w, xw, i, ss )
{
xw = "";
for( i = 1; i < length( w ); i+= 2 )
{
ss = substr( w, i, 2 );
xw = xw (ss in xtab ? xtab[ss] : "x");
}
return xw
}
{ print xlate( $1 ); }
'
There isn't any bound checking to see that the word passed in is an even number of characters. You could also make the function accept both starting and ending positions in the word in addition to the word.
In my opinion, it's bad form to reference field values (e.g. $1) in a function. Better to pass in the contents of the field that you wish to operate on.
If you want to use a while loop (more cumbersome), then you'll need to 'look ahead' before looping. Something like this:
Code:
awk '
BEGIN {
xtab["11"]="a";
xtab["12"]="b";
xtab["13"]="c";
}
# accepts word and starting offset
function xlate( w, start, xw, n )
{
xw = ""
n = substr(w, start, 2) # seed n with first pair
while( n != "" )
{
xw = xw (n in xtab ? xtab[n] : "X")
start = start + 2;
n = substr(w, start, 2) # look ahead to next; exit loop if at end
}
return xw
}
{ print xlate($1, 1) }
'
In my opinion, it's bad form to reference field values (e.g. $1) in a function. Better to pass in the contents of the field that you wish to operate on.
I don't get it. What is the difference between the field value (e.g. $1) and the content of the field? Is it not the same at the end?
I managed to go farther with your code and added a for loop after to increment the start position:
Code:
BEGIN {
xtab["11"]="a";
xtab["12"]="b";
xtab["13"]="c";
}
# accepts word and starting offset
function xlate( w, start)
{
xw = ""
n = substr(w, start, 2) # seed n with first pair
while( n != "" )
{
xw = xw (n in xtab ? xtab[n] : "X")
start = start + 2;
n = substr(w, start, 2) # look ahead to next; exit loop if at end
}
return xw
}
{ for(i=1; i<=2; i++)
print xlate($1, i)
}
it returns:
Code:
abc
aXX
abX
aXX
However, if I want farther to extend the code and refer to this field, for example to print only string without X (as a beginning), is there any way to use again the term "$1" in the rest of the script?
Even when I re-assign the value to $1 it doesn't work!
Code:
BEGIN {
xtab["11"]="a";
xtab["12"]="b";
xtab["13"]="c";
}
# accepts word and starting offset
function xlate( w, start)
{
xw = ""
n = substr(w, start, 2) # seed n with first pair
while( n != "" )
{
xw = xw (n in xtab ? xtab[n] : "X")
start = start + 2;
n = substr(w, start, 2) # look ahead to next; exit loop if at end
}
return xw
}
{ for(i=1; i<=2; i++)
print xlate($1, i)
}
{ for(i=1; i<=2; i++)
print $1 = xlate($1, i)
if($1 !~ /X/){
print $1
}
}
Last edited by beca123456; 09-20-2012 at 04:49 AM..
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"/home/abc/public_html/index.php"
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"/home/xyz/public_html/index.php"
"/home/xyz/public_html/index.php"
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