Match data from array to data from file?

Question

I'm trying to match up the data from an array the lists the days of the week like this:

MONDAY
TUESDAY
WEDNESDAY
THURSDAY
FRIDAY
SATURDAY
SUNDAY

The files data reads like this:

Name1,Tuesday
Name2,Friday
Name3,Sunday
Name4,Wednesday
Name5,Thursday
Name6,Saturday

The output should be:

MONDAY 
TUESDAY Name1
WEDNESDAY Name4
THURSDAY Name5
FRIDAY Name2
SATURDAY Name6
SUNDAY Name3

I am able to cut the data by the comma into two. I was wondering if it's possible to match the data from the file to the data within the array.

Answer 1

If file1 has the days of the week and file2 has the days and names, then:

$ awk -F, 'FNR==NR{a[toupper($2)]=$1;next} {print $1,a[$1]}' file2 file1
MONDAY 
TUESDAY Name1
WEDNESDAY Name4
THURSDAY Name5
FRIDAY Name2
SATURDAY Name6

How it works

• -F,

  Use a comma as the field separator.

• FNR==NR{a[toupper($2)]=$1;next}

  While we are reading through the first named file, file2, add an entry to associative array a with the key as the upper case version of the day and value as the name. Then, skip the rest of the commands and jump to the next line.

• print $1,a[$1]

  If we get to here, we are working on the second file. In that case, print the day and the name that we retrieve from associative array a.