How can we combine two files based on a condition in awk command?

Question

I have two text files which has space seperated values, i want to combine the files based on a key column from both files and output in another file.
location.txt

1 21.5 23
2 24.5 20
3 19.5 19
4 22.5 15
5 24.5 12
6 19.5 12

data.txt which has milllion of data, but i will give simple few entries here,

2004-03-31 03:38:15.757551 2 1 122.153 -3.91901 11.04 2.03397
2004-02-28 00:59:16.02785 3 2 19.9884 37.0933 45.08 2.69964
2004-02-28 01:03:16.33393 11 3 19.3024 38.4629 45.08 2.68742
2004-02-28 01:06:16.013453 17 4 19.1652 38.8039 45.08 2.68742
2004-02-28 01:06:46.778088 18 5 19.175 38.8379 45.08 2.69964
2004-02-28 01:08:45.992524 22 6 19.1456 38.9401 45.08 2.68742

What i trying is to combine these two files based on the key value of column 1 from location.txt and column 4 from data.txt and get the result in format as below by combining all the data from data.txt and column 2 and 3 from location.txt ..

2004-03-31 03:38:15.757551 2 1 122.153 -3.91901 11.04 2.03397 21.5 23
2004-02-28 00:59:16.02785 3 2 19.9884 37.0933 45.08 2.69964 24.5 20
2004-02-28 01:03:16.33393 11 3 19.3024 38.4629 45.08 2.68742 19.5 19
2004-02-28 01:06:16.013453 17 4 19.1652 38.8039 45.08 2.68742 22.5 15
2004-02-28 01:06:46.778088 18 5 19.175 38.8379 45.08 2.69964 24.5 12
2004-02-28 01:08:45.992524 22 6 19.1456 38.9401 45.08 2.68742 19.5 12

I'm using awk command:

awk -F' ' "NR==FNR{label[$1]=$1;x[$1]=$2;y[$1]=$3;next}; ($2==label[$2]){print $0 "," x[$2] y[$3]}" location.txt data.txt > result.txt

But I'm not getting the output as i expected, Can anyone help me fix this? can we get the result file in csv format with space replaced with comma?

Answer 1

With bash and join

join -1 1 -2 4 <(sort -k1,1 -n location.txt) <(sort -k4,4 -n data.txt) -o 2.1,2.2,2.3,2.4,2.5,2.6,2.7,2.8,1.2,1.3

Output:

2004-03-31 03:38:15.757551 2 1 122.153 -3.91901 11.04 2.03397 21.5 23
2004-02-28 00:59:16.02785 3 2 19.9884 37.0933 45.08 2.69964 24.5 20
2004-02-28 01:03:16.33393 11 3 19.3024 38.4629 45.08 2.68742 19.5 19
2004-02-28 01:06:16.013453 17 4 19.1652 38.8039 45.08 2.68742 22.5 15
2004-02-28 01:06:46.778088 18 5 19.175 38.8379 45.08 2.69964 24.5 12
2004-02-28 01:08:45.992524 22 6 19.1456 38.9401 45.08 2.68742 19.5 12

---

See: man join

Answer 2

In awk:

$ awk '
NR==FNR {                  # process location.txt
    a[$1]=$2 OFS $3        # hash using $1 as key
    next                   # next record
}
$4 in a {                  # process data.txt
    print $0,a[$4]         # output record and related location 
}' location.txt  data.txt  # mind the file order
2004-03-31 03:38:15.757551 2 1 122.153 -3.91901 11.04 2.03397 21.5 23
2004-02-28 00:59:16.02785 3 2 19.9884 37.0933 45.08 2.69964 24.5 20
2004-02-28 01:03:16.33393 11 3 19.3024 38.4629 45.08 2.68742 19.5 19
2004-02-28 01:06:16.013453 17 4 19.1652 38.8039 45.08 2.68742 22.5 15
2004-02-28 01:06:46.778088 18 5 19.175 38.8379 45.08 2.69964 24.5 12
2004-02-28 01:08:45.992524 22 6 19.1456 38.9401 45.08 2.68742 19.5 12