Combine two arrays. for in for ?..


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# 1  
Combine two arrays. for in for ?..

Hello all,
I have 2 very long list of elements. f.e.:

List 1
Code:
1 2 3 4 5

List 2
Code:
a b c

How can I combine the two with other. Like this:

Code:
1 a
1 b
1 c
2 a
2 b
2 c
3 a

etc.

Thank you in advance!

I made such construction, but it works very slowSmilie

Code:
declare -a itemid=($(cat ITEMID.txt))
declare -a elementen=($(cat elementen.txt))

for i in ${elementen[@]}
	do 
		for b in ${itemid[@]}
			do
				db2 -x "select DOCID from ICMADMIN."$i" where ITEMID='"$b"'" && echo "$i"
		done
done


Last edited by rbatte1; 01-07-2020 at 02:59 PM..
# 2  
You can save half of the memory by not storing in arrays.
Code:
set -f # for safety: no filename generation
for i in $(cat elementen.txt)
do 
  for b in $(cat ITEMID.txt)
  do
    db2 -x "select DOCID from ICMADMIN."$i" where ITEMID='"$b"'" && echo "$i"
  done
done

bash even allows to replace $(cat ...) with $(< ...).
This User Gave Thanks to MadeInGermany For This Post:
# 3  
Hi
Code:
eval echo {$(tr ' ' , <ITEMID.txt)}{$(tr ' ' , <elementen.txt)} | fmt -1

--- Post updated at 17:50 ---

It’s quite possible
Code:
eval echo {0..10}{$(tr ' ' , <file2)} | fmt -1

or even such
Code:
echo {1..5}{a..c} | fmt -1

--- Post updated at 17:58 ---

Code:
echo -n {1..5}{a..c} | xargs -d' ' -I{} echo {}

--- Post updated at 18:08 ---

I was wrong, did not pay attention to the command "db2"

--- Post updated at 18:37 ---

But continue, very interesting Smilie
Code:
eval echo {$(tr ' ' , <ITEMID.txt)}\' \'{$(tr ' ' , <elementen.txt)} | fold -w4 |
    while read i b; do
        db2 -x "select DOCID from ICMADMIN."$i" where ITEMID='"$b"'" && echo "$i"
    done

should change fold -w4 for grep -o '\w\+ \w\+'

Last edited by nezabudka; 01-07-2020 at 11:52 AM..
# 4  
How about trying, given your shell offers

- the mapfile command
- "here documents",


and db2 reads from stdin,



Code:
mapfile -td" " F1 < file1                                                                                               
mapfile -td" " F2 < file2                                                                                               
IFS=$'\n'
for i in ${F1[*]}
  do    db2 -x  <<< ${F2[*]/#/select DOCID from ICMADMIN.$i where ITEMID= }
  done
db2 -x
select DOCID from ICMADMIN.1 where ITEMID= a
select DOCID from ICMADMIN.1 where ITEMID= b
select DOCID from ICMADMIN.1 where ITEMID= c
db2 -x
select DOCID from ICMADMIN.2 where ITEMID= a
select DOCID from ICMADMIN.2 where ITEMID= b
select DOCID from ICMADMIN.2 where ITEMID= c
db2 -x
select DOCID from ICMADMIN.3 where ITEMID= a
select DOCID from ICMADMIN.3 where ITEMID= b
select DOCID from ICMADMIN.3 where ITEMID= c
db2 -x
select DOCID from ICMADMIN.4 where ITEMID= a
select DOCID from ICMADMIN.4 where ITEMID= b
select DOCID from ICMADMIN.4 where ITEMID= c
db2 -x
select DOCID from ICMADMIN.5 where ITEMID= a
select DOCID from ICMADMIN.5 where ITEMID= b
select DOCID from ICMADMIN.5 where ITEMID= c

This User Gave Thanks to RudiC For This Post:
# 5  
And I managed to throw out an extra command
Code:
eval echo -en "{$(tr ' ' , <file1)}' '{$(tr ' ' , <file2)}'\n'" |
    while read a b; do
        echo "$a $b"
    done

--- Post updated at 20:12 ---

Just how do I know the length of the string?
getconf LINE_MAX ?

--- Post updated at 20:22 ---

it yields out even with such a set
echo -en {1..30000}' '{a..z}'\n'

--- Post updated at 20:33 ---

Or this expression echo {1..5} does not expand into a string like this echo {1,2,3,4,5}

--- Post updated at 20:43 ---

issued all 30,000 lines
Code:
for((i=1;i<30000; i++)); do echo -n "$i "; done >file1
eval echo -en "{$(tr ' ' , <file1)}' '{a..z}'\n'" | while read a b; do echo "$a.$b."; done

Ok

--- Post updated at 21:38 ---

Code:
for i in $(eval echo {$(tr ' ' , <file1)}_{$(tr ' ' , <file2)}); do
    echo "index ${i%_*} value ${i#*_}"
done


Last edited by nezabudka; 01-07-2020 at 02:03 PM..
# 6  
I would think that you are spending a lot of time in your loop repeatedly opening the database connection. Could you build all the queries into a single command file and execute one DB read? The output could be caught to a file or into a variable and then processed further. You might need to add extra columns to the output so you can tell which is from which query if that's necessary.

Can you tell us more about the overall aim of the process and perhaps we can help you towards a more efficient solution. The variable names don't give much away. Perhaps more meaning ful names (even if it takes marginally longer to type) will be far clearer to understand later on.





Kind regards,
Robin
# 7  
Pertaining to post #1: Try:
Code:
join -12 -22 -o 1.1,2.1 <(xargs -n1 <file1) <(xargs -n1 <file2)

This User Gave Thanks to Scrutinizer For This Post:
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