Reinitialization of awk variables - awk

I am struggling with resetting some awk variables. I have multiple lines of the form:
one two three ... ten
with various appearances of each word in every line. I am trying to count the number of times each word is one each line, separate from the counts from the other lines.
this is what I have so far:
{ for(i=length(Num); i>0; i--)
if( Num[i] == "one" )
{
oneCount++
}
else if( Num[i] == "two" )
{
twoCount++
}
else if( Num[i] == "three" )
{
threeCount++
}
...
}
when I print out the count values, the count doesn't reinitialize with each new line. how do i fix this?
any help is much appreciated


You seem very confused. To get a count of each field in a ;-separated line would be:
awk -F';' '{
split("",cnt) # or "delete cnt" if using GNU awk.
for (i=1;i<=NF;i++) {
cnt[$i]++
}
for (word in cnt) {
print word, cnt[word]
}
}' file
Now is there anything else you need it to do?


Try initializing an array in the BEGIN portion to however many variables you'd like to count. You can run a loop in the portion to clear the array at the beginning of every new line.
Alternatively, you could just reset the value of each variable to 0 or null in the portion of the program that executes every line, but I'm guessing you have many variables.

Related

Else syntax error when nesting array formula

I am recieving a syntax error on "else" for this shell:
{for (i=8;i<=NF;i+=3)
{if ($0~"=>") # if-else statement designed to flag file / directory transfers
print "=> flag,"$1"," $2","$3","$4 ","$5","$6","$7"," $(i)","$(i+1)","$(i+2);
{split ($(i+2), array, "/");
for (x in array)
{j++;
a[j] =j;
printf (array[x] ",");}
printf ("%s\n", "");}
else
print "no => flag,"$1"," $2","$3","$4 ","$5","$6","$7"," $(i)","$(i+1)","$(i+2)
}
}
Can't figure out why. If I delete the array block (starting with split()), all is well. But I need to scan the contents of $(i+2), so cutting it does me no good.
Also, if anyone has guidance on a good list of how to interpret error messages, that would be great.
Thanks for your advice.
EDIT: here is the above script laid out with sensible formatting:
{
for (i=8;i<=NF;i+=3) {
if ($0~"=>") # if-else statement designed to flag file / directory transfers
print "=> flag,"$1"," $2","$3","$4 ","$5","$6","$7"," $(i)","$(i+1)","$(i+2);
{
split ($(i+2), array, "/");
for (x in array) {
j++;
a[j] =j;
printf (array[x] ",");
}
printf ("%s\n", "");
}
else
print "no => flag,"$1"," $2","$3","$4 ","$5","$6","$7"," $(i)","$(i+1)","$(i+2)
}
}

First thing first, since you didn't post any samples of input and expected output so didn't test it at all. Could you please try following, I hope you are running this in .awk script style. Also these are mostly syntax/cosmetic changes NOT on logic part, since no background was given on problem.
BEGIN{
OFS=","
}
{
for (i=8;i<=NF;i+=3){
if ($0~/=>/){
print "=> flag,"$1,$2,$3,$4,$5,$6,$7,$(i),$(i+1),$(i+2)
split ($(i+2), array, "/");
for(x in array){
j++;
a[j] =j;
printf (array[x] ",")
}
printf ("%s\n", "")
}
else{
print "no => flag",$1,$2,$3,$4,$5,$6,$7,$(i),$(i+1),$(i+2)
}
}
}
Problems fixed in OP's attempt:
{ starting curly braces(which indicates that if condition of for loop with multiple statements is started) could be in last of the line where they are present, NOT in next line, for better visibility purposes, I fixed in for loop and if condition first.
Since you are using regexp matching with a pattern so I fixed from $0~"=>" TO $0~/=>/.
Added BEGIN section in your attempt where I have set OFS(output field separator) value to , so that you need NOT to print like "," to print comma between variables, just , between variables will do the trick.
Fixed indentation, so that we are NOT confused where to close loop/condition and where to NOT.

How to return 0 if awk returns null from processing an expression?

I currently have a awk method to parse through whether or not an expression output contains more than one line. If it does, it aggregates and prints the sum. For example:
someexpression=$'JOBID PARTITION NAME USER ST TIME NODES NODELIST(REASON)'
might be the one-liner where it DOESN'T yield any information. Then,
echo "$someexpression" | awk '
NR>1 {a[$4]++}
END {
for (i in a) {
printf "%d\n", a[i]
}
}'
this will yield NULL or an empty return. Instead, I would like to have it return a numeric value of $0$ if empty. How can I modify the above to do this?

Nothing in UNIX "returns" anything (despite the unfortunately named keyword for setting the exit status of a function), everything (tools, functions, scripts) outputs X and exits with status Y.
Consider these 2 identical functions named foo(), one in C and one in shell:
C (x=foo() means set x to the return code of foo()):
foo() {
printf "7\n"; // this is outputting 7 from the full program
return 3; // this is returning 3 from this function
}
x=foo(); <- 7 is output on screen and x has value '3'
shell (x=foo means set x to the output of foo()):
foo() {
printf "7\n"; # this is outputting 7 from just this function
return 3; # this is setting this functions exit status to 3
}
x=foo <- nothing is output on screen, x has value '7', and '$?' has value '3'
Note that what the return statement does is vastly different in each. Within an awk script, printing and return codes from functions behave the same as they do in C but in terms of a call to the awk tool, externally it behaves the same as every other UNIX tool and shell script and produces output and sets an exit status.
So when discussing anything in UNIX avoid using the term "return" as it's imprecise and ambiguous and so different people will think you mean "output" while others think you mean "exit status".
In this case I assume you mean "output" BUT you should instead consider setting a non-zero exit status when there's no match like grep does, e.g.:
echo "$someexpression" | awk '
NR>1 {a[$4]++}
END {
for (i in a) {
print a[i]
}
exit (NR < 2)
}'
and then your code that uses the above can test for the success/fail exit status rather than testing for a specific output value, just like if you were doing the equivalent with grep.
You can of course tweak the above to:
echo "$someexpression" | awk '
NR>1 {a[$4]++}
END {
if ( NR > 1 ) {
for (i in a) {
print a[i]
}
}
else {
print "$0$"
exit 1
}
}'
if necessary and then you have both a specific output value and a success/fail exit status.

You may keep a flag inside for loop to detect whether loop has executed or not:
echo "$someexpression" |
awk 'NR>1 {
a[$4]++
}
END
{
for (i in a) {
p = 1
printf "%d\n", a[i]
}
if (!p)
print "$0$"
}'
$0$

Print smallest integer from file using awk custom function?

awk function looks like this in a file name fun.awk:
{
print small()
}
function small()
{
a[NR]=$0
smal=0
for(i=1;i<=3;i++)
{
if( a[i]<a[i+1])
smal=a[i]
else
smal=a[i+1]
}
return smal
}
The contents of awk.write:
1
23
32
The awk command is:
awk -f fun.awk awk.write
It gives me no result? Why?

I think you are going about this the wrong way. In awk, one approach might be:
NR == 1 {
small = $0
}
$0 < small {
small = $0
}
END {
print small
}
which simply simply sets small to the smallest integer we've seen so far on each line, and prints it at the end. (Note: you need to start with a initializing small on the first line.
A simpler approach might just be to sort the lines as numbers with sort, and pick the first one.

Awk command to insert corresponding line numbers except for blank lines

I'm doing an assignment at the moment and the question that's stumped me is:
"Write an awk command to insert the corresponding line number before
each line in the text file above. The blank line should NOT be
numbered in this case."
I have an answer, but I'm struggling to find the explanation of what each component does.
The command is:
awk '{print (NF? ++a " " :"") $0}' <textfile.txt>
I know that NF is the field number, and that $0 refers to the whole input record. I tried playing around with the command to find what does what, but it always seems to have syntax errors whenever I omit something.
So, my question is what does each component do? What does the ++a do? The ? after NF? and what does the bit with the quotations do?
Thanks in advance!

The instruction ... ? ... : ... it's an if-else. So, it's the same as:
if ( NF > 0 ) {
++a;
print a " " $0;
} else {
print $0;
}
a is a variable that is only incremented when found a line with fields.

print (NF? ++a " " :"") $0
a ternary operator has been used in your solution.
for a blank line NF will be 0 always
so
cond?true case:false case
if NF is >0 then print a or else print ""
a++ says that after printing increment a by 1 which will be used for next non blank line processing.
awk 'BEGIN{count=1}{if($0~/^$/){print}else{print count,$0;count++}}' your_file
tested below:
> cat temp.cc
int main ()
{
}
> awk 'BEGIN{count=1}{if($0~/^$/){print}else{print count,$0;count++}}' temp.cc
1 int main ()
2 {
3 }
>

Awk Iterate through several Arrays in a for loop

I have created an awk program to go through the columns of a file and count each distinct word and then output totals into separate files
awk -F"$delim" {Field_Arr1[$1]++; Field_Arr2[$2]++; Field_Arr3[$3]++; Field_Arr4[$4]++};
END{\
# output fields
out_field1="top_field1"
out_field2="top_field2"
out_field3="top_field3"
out_field4="top_field4"
for( i=1; i <= NF; i++)
{
for (element in Field_Arr$i)
{
print element"\t"Field_Arr$i[element] >>out_field$i;
}
}
}' inputfile
but I don't know the appropriate syntax, so that the for loop will iterate through Field_Arr1, Field_Arr2, Field_Arr3, Field_Arr4?
I have tried using: i, $i, ${i}, {i}, "$i", and "i".
Am I trying the wrong approach or is there a way to change Field_Arr$i to Field_Arr1..4?
Thanks for the advice.

awk variables don't work that way; you'll have to do them individually by name, or use fake multidimensional arrays and parse out the components, something along the lines of:
{Field_Arr[1, $1]++; Field_Arr[2, $2]++; Field_Arr[3, $3]++; Field_Arr[4, $4]++}
END {
for (elt in Field_Arr) {
split(elt, ec, SUBSEP)
print ec[2] "\t" Field_Arr[elt] >> ("top_field" ec[1])
}
}

To count the frequencies for each column (3 in my example), try this
# Print list of word frequencies
function p_array(t,a) {
print t
for (i in a) {
print i, a[i]
}
}
{
c1[$1]++
c2[$1]++
c3[$1]++
}
END {
p_array("1st col",c1)
p_array("2nd col",c2)
p_array("3rd col",c3)
}