Sorting the contents within a column using Shell Script Line by Line in a File - shell

Question

I am Sorting a File using a column using the command -
cat myFile | sort -u -k3
Now i want to Sort Data within a Column of a File. Can anyone please help and tell me how can i achieve it?
My Data Looks like this in the File names Student.csv -
Name,Age,Marks,Grades
Sam,21,"34,56,21,67","C,B,D,A"
Josh,25,"90,89,78,45","A,A,B,C"
Output-
Name,Age,Marks,Grades
Sam,21,"21,34,56,67","A,B,C,D"
Josh,25,"45,78,89,90","A,A,B,C"
Will Appreciate the help, Thanks

Answer 1

You should export your CSV with a field separator that does not exist within the texts. Otherwise it becomes hugely cumbersome to deal with this.
Afterwards you can easily sort by specifying the separator and the field.
Example if you would use | as separator:
Name|Age|Marks|Grades
Sam|21|"34,56,21,67"|"C,B,D,A"
Josh|25|"90,89,78,45"|"A,A,B,C"
Then execute:
cat myFile | sort -u -k3 -t\|
or:
sort -u -k3 -t\| <myFile
Afterwards you could be putting your semi-colons back:
sort -u -k3 -t\| <myFile | sed 's/|/;/g'

Answer 2

Did it, but I'm too tired to explain how; brain's hitting a brick wall. There's a lot to unpack there, and it'll take half-a-day to explain. I'll write all the steps in a couple hours after I get a nap in, otherwise there's gonna be 50 typos in that description.
cat Student.csv | head -n1 && cat Student.csv | tail -n+2 | awk -F \" '{split($2,a,",");asort(a);b="";for(i in a)b=b a[i] ",";split($4,c,",");asort(c);d="";for(i in c)d=d c[i] ",";printf "%s\"%s\",\"%s\"\n",$1,substr(b,1,length(b)-1),substr(d,1,length(d)-1)}'
Alternatively:
cat Student.csv | tee >(head -n1) >(tail -n+2 | awk -F \" '{split($2,a,",");asort(a);b="";for(i in a)b=b a[i] ",";split($4,c,",");asort(c);d="";for(i in c)d=d c[i] ",";printf "%s\"%s\",\"%s\"\n",$1,substr(b,1,length(b)-1),substr(d,1,length(d)-1)}') >/dev/null ; sleep 0.1
Output:
Name,Age,Marks,Grades
Sam,21,"21,34,56,67","A,B,C,D"
Josh,25,"45,78,89,90","A,A,B,C"
https://www.tutorialspoint.com/awk/index.htm
Edit -- 'kay, the explaination:
cat concatenates (glues) files together, but when you just give it one arg, then that's what it prints out.
You can do the next part in one or two steps, I'll explain the first method. | pipe directs the output to another command. We all know this, or we wouldn't be here right now... however someday, someone will come across this post, and wonder what it does.
head prints out the first few lines of what you give it. Here, I specified -n1 number of lines = one, so it would print out the header:
Name,Age,Marks,Grades
&& continues to the next command, so long as that initial instruction was a success.
cat Student.csv again, but this time piped into tail, which prints the last few lines, of whatever you give it. -n+2 specifies to spit out everything from line number 2, and beyond.
We then pipe those contents into AWK https://en.wikipedia.org/wiki/AWK ...I'm sure you could do it with sed https://en.wikipedia.org/wiki/Sed, and I started with that, but sed tends to be more simple than awk, so you'd need to do far more chained-commands to achieve the same thing. Lisp might be able to do it more concicely, but it sounded like you were asking for shell builtins. Python's also decent with strings, but again, sh.
-F \" delegates a literal " as the field separator, so that we can group the contents into 3 categories:
Sam,21, " 34,56,21,67 " , "C,B,D,A"
$1 = Sam,21,
$2 = 34,56,21,67
$3 = ,
$4 = C,B,D,A
You actually get 4, but I'm throwing out that comma in the third position. It's easy enough to put it back in.
We now need to sort those numbers, so split($2,a,",") returns an array, in this case, named a, from the contents of $2, which has been delimited by the , symbol.
a = [ 34, 56, 21, 67 ]
; separates AWK commands, you can mostly ignore those. If there were simply a space, awk would try to concatenate items together, and we don't want that yet.
Next, array sort asort( a ), the contents of a -- https://www.tutorialspoint.com/awk/awk_string_functions.htm
a = [ 21, 34, 56, 67 ]
Here would be a perfect time for Python's string .join() method https://www.w3schools.com/python/ref_string_join.asp
However, we don't have that available to us, and AWK doens't seem to have it, as far as I know, so we have to roll our own here. So construct string, b, whose contents will be appended by each item in a. Single-quotes often won't do in commandline, so you'll see double-quotes.
b=""
for( i in a ) b=b a[i] ","
b begins empty. Iterating a for-loop over a's contents, we arrive at an appending which includes commas. Leave the trailing comma for now, it'll get trimmed off in a bit.
21,34,56,67,
Exact same procedure for $4, but we name the array c this time, and the string in which those contents are contatenaded with commas, d -- split( $4, c, "," ) ; asort( c ) ; d="" ; for( i in c ) d=d c[i] "," You can name them anything you like, just happened to have ABCD staring me in the face from those grade listings, so that's what I went with.
OK, now we have everything we need.
$1 = Sam,21,
b = 21,34,56,67,
d = A,B,C,D,
Let's format a string so they're all together.
printf "%s\"%s\",\"%s\"\n"
This will print $1 in the first %s string position, then a literal double-quote,
b into the second %s string position, next ",",
followed by d in the third %s position,
all wrapped up with a final double-quote and a newline.
However, b and d both have trailing commas, so we trim those off with AWK's substr() command. -- https://www.tutorialspoint.com/awk/awk_string_functions.htm Knowing where to begin is easy enough, but we need to chop those at one-from-the-end.
substr( b, 1, length(b) -1 )
substr( d, 1, length(d) -1 )
It'd be nice if you could just specify -2, and have it count backwards, like you can in Lua, Python, et al... but that doesn't seem to do in AWK, so whatevs. Ya live, ya learn. And there you have it, all your ducks in a row.
Sam,21,"21,34,56,67","A,B,C,D"
This does, maybe not elegantly, but it's within the required guidelines. I'm sure there's possibilities of code-golfing in there somewhere, but it's solid logic you can follow.