mjhjmtu

I have huuuge sets of data consisting of 3 columns. I'd like to be able to find max and min values in the third column (there is mix of zeros and then negative values, so I want to find max negative and min negative value) and then print that particular row. How can I do that?

example input:

-6.4 -3.6 -0.00
-6.4 -3.5 -0.00
-6.4 -3.5 -0.00
-6.4 -3.5 -0.00
.
.
.
-2.4 -1.6 -14.50
-2.4 -1.5 -14.49
-2.4 -1.5 -14.49
-2.4 -1.5 -14.49
.
.
.
-5.4 -2.6 -4.52
-5.4 -2.6 -4.53
-5.4 -2.6 -4.50
-5.4 -2.6 -0.00
-5.4 -2.6 -0.00

output:
min: -2.4 -1.6 -14.50

max: -5.4 -2.6 -4.50

You've already accepted an answer but here's an easier way:

egrep -v "0.00|^." file.txt | awk 'NR==1 print "min:",$0 ENDprint"max:",$0'

Output:

min: -2.4 -1.6 -14.50
max: -5.4 -2.6 -4.50

-As you don't want the zeroes even though they're actually the largest number, the egrep -v command prints all lines except those starting with 0.00 and beginning with a "."

-After the above, the lines are already in order from smallest to largest. awk then prints the first line with "min:" prepended and the last line with "max:" prepended.

If the values in that column happen to not be in order, you can pipe sort -k3 (assuming it's the third column you want to sort) after the egrep command and then pipe it into the awk command after it.

I would suggest doing this in Python. If your data is whitespace-separated, it will be something as simple as:

minVal = None
maxVal = None
with open('file') as f:
 for line in f:
 # default: split on whitespace.
 third = int(line.split()[2])
 if not minVal:
 # initialize the values
 minVal = third
 maxVal = third
 else:
 minVal = min(third, minVal)
 maxVal = max(third, maxVal)

print("min", minVal)
print("max", maxVal)

EDIT: given that you want the entire row, you should instead store minRow and maxRow. It the past, when I have had to do something like this, I have used a custom min/max function. Both take a key argument to specify a custom function.

You can try with awk :

awk -v 'f=1' '
 NF==3 
 min = min < $3 ? min : $3
 if ( min != oldmin ) 
 a = $0
 oldmin = min
 
 if ( $3 < 0 ) 
 if ( f ) 
 max = min
 f = 0
 
 max = max > $3 ? max : $3
 
 if ( max != oldmax ) 
 oldmax = max
 b = $0
 
 
 END 
 print "min : " a RS "max : " b
 
' infile