How do I find the number of elements in a column greater than a given number in Linux? - linux

Question

I have a text file of list of students with Marks and I want to find how many of them secured more than 80 in Maths, Physics and then Maths and Physics combined. What should be the Linux command to do this?
The text file is here:
#name maths phy
Manila 78 29
Shikhar 49 78
Vandana 65 87
Priyansh 75 22
Bina 52 69
Chitransh 98 93
William 88 73
Kaushal 38 85
Dilruba 65 94
Lalremruata 34 45
Qasim 58 62
Nitya 81 89
Jennita 96 91
Shobha 71 63
Talim 77 88

Answer 1

This can be achieved using awk (don't use grep because this is not fit for number arithmetic). An example:
cat test.txt | awk '{if ($2>80 || $3>80) print $1 " " $2 " " $3}'
This needs to be improved: how to remove the cat command, how to check the sum of both columns, why is the title present, ...? But at least you have something to start.

Answer 2

Try this, and adapt it to your taste:
$ awk '/^[^#]/{
limit = 80;
comb = $2 + $3;
if ($2 > limit && $3 > limit)
print $1, $2, $3, "both";
else if ($2 > limit)
print $1, $2, $3, "maths";
else if ($3 > limit)
print $1, $2, $3, "physics";
else if (comb > limit)
print $1, $2, $3, "combined";
}' <<EOF
#name maths phy
Manila 78 29
Shikhar 49 78
Vandana 65 87
Priyansh 75 22
Bina 52 69
Chitransh 98 93
William 88 73
Kaushal 38 85
Dilruba 65 94
Lalremruata 34 45
Qasim 58 62
Nitya 81 89
Jennita 96 91
Shobha 71 63
Talim 77 88
EOF
which produces the following:
Manila 78 29 combined
Shikhar 49 78 combined
Vandana 65 87 physics
Priyansh 75 22 combined
Bina 52 69 combined
Chitransh 98 93 both
William 88 73 maths
Kaushal 38 85 physics
Dilruba 65 94 physics
Qasim 58 62 combined
Nitya 81 89 both
Jennita 96 91 both
Shobha 71 63 combined
Talim 77 88 physics
If you want it to be read from a file, then use it as:
$ awk '/^[^#]/{
limit = 80;
comb = $2 + $3;
if ($2 > limit && $3 > limit)
print $1, $2, $3, "both";
else if ($2 > limit)
print $1, $2, $3, "maths";
else if ($3 > limit)
print $1, $2, $3, "physics";
else if (comb > limit)
print $1, $2, $3, "combined";
}' marks.txt
the awk script
will read all lines that have not a # in the first column, what will allow you to introduce comments, as the header with the course name.
will permit you to configure easily a trigger level, as the limit variable is initialized in one place and used as a constant.
you can adapt the criterion to what you want to get, even the students that don't pass any of the two courses.
Note:
If you want to do variable substitution inside the awk script, beware that awk uses $<n> notation to refer to input words, which is also used and expanded by the shell, so you you need to do shell variable expansion, the best approach is to close the single quotes and open double quotes on the variable to be expanded only, so you don't get confused which variable will be expanded by the shell and which by awk. Example:
$ export TRIGGER=95
$ awk '/^[^#]/{
limit = '"$TRIGGER"';
comb = $2 + $3;
if ($2 > limit && $3 > limit)
print $1, $2, $3, "both";
else if ($2 > limit)
print $1, $2, $3, "maths";
else if ($3 > limit)
print $1, $2, $3, "physics";
else if (comb > limit)
print $1, $2, $3, "combined";
}'