Performing calculations based on customer ID in comma-separated file [duplicate] - unix

Question

This question already has an answer here:
Use awk to sum or average for each unique ID
(1 answer)
Closed 6 years ago.
I have a file that contains several comma-separated columns, including a customer ID in the first column.
One customer ID may occur on several rows, but always refers to the same real customer.
How do I run basic calculations in a shell script based on this ID column? For example, calculating the sum of the mileages (the 5th field) for the given customer ID.
102,305,Jin,Kerala,40
104,308,Paul,US,45
105,350,Nina,AUS,50
102,390,Jin,Kerala,10
104,395,Paul,US,35
102,399,Jin,Kerala,35
5th field is the mileage, 1st field is the customer ID.

Answer 1

This is a simple awk script that will sum up the mileages and print the customer IDs together with the sums at the end:
#!/usr/bin/awk -f
BEGIN { FS = "," }
{
customer_id = $1;
mileage = $5;
total_mileage[customer_id] += mileage;
}
END {
for (customer_id in total_mileage) {
print customer_id, total_mileage[customer_id];
}
}
To run (after making it executable with chmod +x script.awk):
$ ./script.awk data.in
102 85
104 80
105 50
Alternatively, as a "one-liner":
$ awk -F, '{t[$1]+=$5} END {for (c in t){print c,t[c]}}' data.in
102 85
104 80
105 50

Answer 2

While I agree with #wilx that using a database might be smarter, this sample awk script should get you started:
awk -v FS=',' '{miles[$1] += $5}
END { for (customerid in miles) {
print customerid, miles[customerid]; } }' customers

Answer 3

You can get a list of unique IDs using something like (assuming the first column is the ID):
awk '{print $1}' inputFile | sort -u
This outputs the first field of every single line in the input file inputFile, sorts them and removes duplicates.
You can then use that method with a bash loop to process each of the unique IDs with another awk command to perform some action on them. In the following snippet, I print out the matching lines for each ID:
for id in $(awk '{print $1}' inputFile | sort -u) ; do
echo "${id}:"
awk -vid=${id} '$1==id {print " "$0)' inputFile
done
In that code, for each individual ID, it first outputs the ID then uses awk to only process lines matching that ID. The action carried out is to output the full line with indentation.
Of course, you can do anything you wish with the lines matching each ID. As shown below, an example more closely matching your requirements.
First, here's an input file I used for testing - we can assume field 1 is the customer ID and field 2 the mileage:
$ cat inputFile
a 1
b 2
c 3
a 4
b 5
c 6
a 7
b 8
c 9
b 10
c 11
c 12
And here's a command-line transcript of the method proposed (note that $ and + are input prompt and continuation prompt respectively, they are not part of the actual commands):
$ for id in $(awk '{print $1}' inputFile | sort -u) ; do
+ awk -vid=${id} '
+ $1==id {print $0; sum += $2 }
+ END {print "Total: "sum; print }
+ ' inputFile
+ done
a 1
a 4
a 7
Total: 12
b 2
b 5
b 8
b 10
Total: 25
c 3
c 6
c 9
c 11
c 12
Total: 41
Keep in mind that, for non-huge data sets, it's also possible to do this in a single pass awk script, using associative arrays to store the totals then outputting all the data in the END block. I myself tend to prefer the multi-pass approach myself since it minimises the possibility of running out of memory. The trade-off, of course, is that it will no doubt take longer since you're processing the file more than once.
For a single-pass solution, you can use something like:
$ awk '{sum[$1] += $2} {for (key in sum) { print key": "sum[key]}}' inputFile
which gives you:
a: 12
b: 25
c: 41