Check if something isn't in an array

Mark_667 · 10-23-2018, 05:47 AM

Sorry for the basic question but I have an array that's an exclusion list e.g.

Code:

exclusionList[0]='item 1'
exclusionList[1]='item 2'

While iterating over a larger list I want to check whether the current item is in the array and skip it if it is. I tried using the following

Code:

if [ '$exclusionList[*]' != '$currentItem' ]; then

but it never seems to match, what am I missing?

rtmistler · 10-23-2018, 06:43 AM

What language? (Appears to be bash, just not sure)

And if it is bash, have you turned on debug?

rtmistler · 10-23-2018, 06:50 AM

If bash, I think the notation should be:

Code:

'${exclusionList[*]}'

Because if you go to echo that array, you have to do it like this:

Code:

echo ${exclusionList[*]}

l0f4r0 · 10-23-2018, 06:54 AM

In bash, I would say something like:

Code:

for item in ${#exclusionList[@]}
do
   if [[ $item != $currentItem ]]
   then
      <put_code here>
   fi
done

Of course you need to adapt it to your needs.

BW-userx · 10-23-2018, 07:08 AM

that's how I'd do it, loop through the array and check against it. if 'true' then else 'not [true]' fi
but

Code:

$array[0]=H 
$array[1]=B 
$array[2]=J
 
curr=B

#this way I get no return 
$for d in ${#array[@]} ;  do if [[ $d == $curr ]] ; then echo got it $curr ; fi; done

for d in ${#array[@]} ;  do if [[ ${array[$d]} == $curr ]] ; then echo got it $curr ; fi; done

#here I get a return

for d in ${!array[@]} ;  do if [[ ${array[$d]} == $curr ]] ; then echo got it $curr ; fi; done
got it B

I'd like to point out.

Mark_667 · 10-23-2018, 09:35 AM

Didn't know bash had debug flags. Googled it and found +x and -x which helped a lot.

Currently it looks like this:

Code:

exclusionList[0]='item 1'
exclusionList[1]='item 2'
exclusionList[2]='item 3'

testInput = 'item 1'

for item in $(echo "$testInput")
do
	for (( item=0; item<=2; item++ ))
	do
		if [[ $exclusionList[$item] == $item ]]
		then
			match=True
			break;
		fi
	done
	if [ $match==True ]
	then
		echo 'Excluding' $item
		break;
	else
		echo 'Including ' $item
	fi
done

From the debug I can see it only seems to be evaluating the testInput against the first array entry?

BW-userx · 10-23-2018, 09:51 AM

Quote:

Originally Posted by Mark_667

Didn't know bash had debug flags. Googled it and found +x and -x which helped a lot.

From the debug I can see it only seems to be evaluating the testInput against the first array entry?

Code:

testInput = 'item 1'
#needs to be
testInput='item 1'

no spaces between =

what are you trying to match the names or the number of the element?

what is this for

Code:

#for item in $(echo "$testInput")
#do

looky here

Code:

#!/bin/bash

set -x

exclusionList[0]='item 1'
exclusionList[1]='item 2'
exclusionList[2]='item 3'

testInput='item 1'

item=0
match=false

for item in $(echo "$testInput")
do
#	for item in ${!exclusionList[@]}
for (( item=0; item<=2; item++ ))
	do
		if [[ $exclusionList[$item] == $item ]]
		then
			match=True
			echo $item
			echo ${exclusionList[$item]}
			break;
		else
			echo "no match"
		fi
	done
	
	if [ $match == 'True' ]
	then
		echo 'Excluding' $item
		break;
	else
		echo 'Including ' $item
	fi
	

done

output set -x

Code:

└──╼ $./checkarrays
+ exclusionList[0]='item 1'
+ exclusionList[1]='item 2'
+ exclusionList[2]='item 3'
+ testInput='item 1'
+ item=0
+ match=false
++ echo 'item 1'
+ for item in $(echo "$testInput")
+ (( item=0 ))
+ (( item<=2 ))
+ [[ item 1[0] == 0 ]]
+ echo 'no match'
no match
+ (( item++  ))
+ (( item<=2 ))
+ [[ item 1[1] == 1 ]]
+ echo 'no match'
no match
+ (( item++  ))
+ (( item<=2 ))
+ [[ item 1[2] == 2 ]]
+ echo 'no match'
no match
+ (( item++  ))
+ (( item<=2 ))
+ '[' false == True ']'
+ echo 'Including ' 3
Including  3
+ for item in $(echo "$testInput")
+ (( item=0 ))
+ (( item<=2 ))
+ [[ item 1[0] == 0 ]]
+ echo 'no match'
no match
+ (( item++  ))
+ (( item<=2 ))
+ [[ item 1[1] == 1 ]]
+ echo 'no match'
no match
+ (( item++  ))
+ (( item<=2 ))
+ [[ item 1[2] == 2 ]]
+ echo 'no match'
no match
+ (( item++  ))
+ (( item<=2 ))
+ '[' false == True ']'
+ echo 'Including ' 3
Including  3

you're checking numbers against text, what is inside of the elements.

you reference arrays like this

Code:

${exclusionList[$item]}

to check the value within the array elements

Code:

if [[ ${exclusionList[$item]} == $testInput ]]

Mark_667 · 10-23-2018, 10:08 AM

Thanks, am trying to match the names so if the testInput contains a value in the array it'll be excluded.
The testInput contains multiple values, the outer loop iterates over each one. The inner loop checks this against each entry in the array to see if it should be processed. Sorry if this wasn't clear.

Quote:

you're checking numbers against text

Didn't know what you meant by this until I saw the code you posted. You reused the $item change the outer loop to:

Code:

for currentItem in $(echo "$testInput")

and the following if to:

Code:

if [[ $exclusionList[$item] == $currentItem ]]

michaelk · 10-23-2018, 10:18 AM

Code:

for item in $(echo "$testInput")

Code:

for (( item=0; item<=2; item++ ))

You have two loops with the same variable name.

Mark_667 · 10-23-2018, 10:22 AM

Quote:

Originally Posted by michaelk

You have two loops with the same variable.

Sorry, that was a copy and paste fail on my part that gives a misleading idea of what I'm working with. See my last post for the correction.

BW-userx · 10-23-2018, 10:26 AM

Quote:

Originally Posted by Mark_667

Thanks, am trying to match the names so if the testInput contains a value in the array it'll be excluded.
The testInput contains multiple values, the outer loop iterates over each one. The inner loop checks this against each entry in the array to see if it should be processed. Sorry if this wasn't clear.

Didn't know what you meant by this until I saw the code you posted. You reused the $item change the outer loop to:

Code:

for currentItem in $(echo "$testInput")

and the following if to:

Code:

if [[ $exclusionList[$item] == $currentItem ]]

your code says your first loop is redundant. the second loop is trying to match the number of the loop cycle against the name (value) within the array element.

your test var contains only 1 (one) value. It looks like you're wanting to match that value to one of the elements within the array, if no match then your 'match' var value=false.

https://www.unix.com/shell-programmi...ll-script.html

Code:

#!/bin/bash

set -x
#initiate array
exclusionList[0]='item 1'
exclusionList[1]='item 2'
exclusionList[2]='item 3'

#initiate variables
testInput='item 1'
item=0
match=false

	#same as second for condition
	#for item in ${!exclusionList[@]}

	for (( item=0; item<=2; item++ ))
	do
	 #looks at value within each element of array
	 #then compares it against the value within
	 # testInput var
	if [[ ${exclusionList[$item]} == $testInput ]]
		then
			match=True
			echo $item
			echo ${exclusionList[$item]}
			#if match break out of loop
			break;
		else
			echo "no match"
		fi
	done
	
	#then check the value of the match
        #flag
	if [ "$match" == 'True' ]
	then
		echo 'Excluding' $item
	 
	else
		echo 'Including ' $item
	fi


#run this within your script to see what
# item is doing

for item in ${!exclusionList[@]}
do
	echo $item
done

for (( item=0; item<=2; item++ ))
do
	echo $item
done

how array's and loops work
https://www.cyberciti.biz/faq/bash-for-loop-array/

pan64 · 10-23-2018, 01:05 PM

using space in items make it hard to handle.

Code:

for item in $(echo "$testInput")
# can be replaced by:
for item in $testInput

I suggest you to use associative arrays, that makes it much more easy:

Code:

exclusionList["item 1"]=1
exclusionList["item 2"]=1
exclusionList["item 3"]=1
...

You only need to check if exclusionList["anything"] exists.

Otherwise I suggest you to try www.shellcheck.net to check your script.

NevemTeve · 10-23-2018, 01:44 PM

Untested:

Code:

declare -A Excludes
Excludes['this']=1
Excludes['that']=1
if [ -n "${Exludes["$testvalue"]}" ]; then
 ...
fi

Oh I was late

michaelk · 10-23-2018, 01:45 PM

To elaborate on pan64's post.

Code:

testInput='item 1'

for currentitem in $(echo "$testInput")
do
  echo $currentitem
done

The for loop uses IFS to split the string which uses a space by default so the value of $currentitem will be
item
1

Code:

testInput='item 1'

for currentitem in "$testInput"
do
  echo $currentitem
done

However, the above loop will not split the string and so $currentitem will only loop once and be the value of
"item 1"

These are probably only test cases and may not be the real values. You can change the default value of IFS but that could also cause other problems if not careful with your loops.

Mark_667 · 10-23-2018, 03:09 PM

Thanks, wasn't aware of the gotcha with spaces. I based it on another script which had the same set of inputs consisting of strings containing spaces so I didn't suspect that.