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Question

Can someone show me a way to find the largest positive number using awk,sed or some sort of unix shell program? I'm using Linux RHEL with KSH. The input may have 8 columns worth of data with N/A as one of the possible values.

SAMPLE INPUT

1252.2 1251.8 N/A N/A 
-31.9 -33.2 N/A N/A 
-1172.4 -1174.4 N/A N/A 
-6.5 -6.4 N/A N/A 
-.3 -.3 N/A N/A 
1351.8 1351.8 N/A N/A 
38.3 38.0 N/A N/A 
-21.6 -21.9 N/A N/A 
-4.7 -4.5 N/A N/A 
-5.0 -2.9 N/A N/A 
3.1 3.3 N/A N/A 
-20.1 -20.3 N/A N/A 
-199.1 -199.3 N/A N/A 
346.5 346.7 N/A N/A 
-.8 -.4 N/A N/A 
14.8 14.7 N/A N/A 
8.4 8.4 N/A N/A 
-18.2 -18.2 N/A N/A 
-43.7 -43.6 N/A N/A

Desired output

Largest number is 1351.8

score 1 · Accepted Answer · 2019-02-24 05:08:46Z

A bash-style solution using tr, sort and head

echo $(< file) | tr ' ' 'n' | sort -rn | head -1

echo $(< file) reads the file and echoes the result. But as we don't have quotes around it (echo "$(< file)" does the same as cat file) the content is one long string with newlines removed and whitespace squeezed

| tr ' ' 'n' pipes the result through tr replacing each space character with a newline

| sort -rn pipes the result to sort, sorting all lines in reversed (-r) numeric (-n) order (largest number first)

| head -1 pipes the result to head to output the first line

replacing head -1 with tail -1 will give the smallest. Nice. This is exactly what i want. — Feb 24 at 5:16
I don't see the point of the echo $(<file), starting the pipeline with a <file tr -s ' ' 'n' should suffice — Feb 24 at 5:18

steeldriversteeldriver 37.2k45287 · Accepted Answer · 2019-02-24 02:54:57Z

3

With Awk, forcing numeric evaluation of the N/A entries:

awk 'for (i=1;i<=NF;i++) max = $i+0 > max ? $i : max ENDprint "Largest number is " max' data

answered Feb 24 at 2:54

steeldriver

37.2k45287

Why the $i+0 in the max assignment's test ? Am I missing something ?

– Cbhihe
Feb 24 at 12:00

1

@Cbhihe it was intended to prevent unintended lexical comparison of any non-numeric fields - but perhaps it's not necessary

– steeldriver
Feb 24 at 16:54

add a comment |

Cbhihe 4021618 · Accepted Answer · 2019-02-24 13:54:28Z

2

One way can be:

perl -lane '$_>$m and $m=$_ for @F}print $m' sample.txt

Explanation:

-n option will process your input file on a per line basis.

-e option will apply the Perl code following it, to every line of input read.

-a option will split each line as it is read into individual fields and store them in an array @F.

-l option will make RS=ORS="n"

for @F will loop over each field, the current field being held in $_.

We compare the current field with the maximum and in case it it more than max, update max.

When we are done comparing,

2

One way can be:

perl -lane '$_>$m and $m=$_ for @Fprint $m' sample.txt

Explanation:

-n option will process your input file on a per line basis.

-e option will apply the Perl code following it, to every line of input read.

-a option will split each line as it is read into individual fields and store them in an array @F.

-l option will make RS=ORS="n"

for @F will loop over each field, the current field being held in $_.

We compare the current field with the maximum and in case it it more than max, update max.

When we are done comparing,

2

One way can be:

perl -lane '$_>$m and $m=$_ for @Fprint $m' sample.txt

Explanation:

-n option will process your input file on a per line basis.

-e option will apply the Perl code following it, to every line of input read.

-a option will split each line as it is read into individual fields and store them in an array @F.

-l option will make RS=ORS="n"

for @F will loop over each field, the current field being held in $_.

We compare the current field with the maximum and in case it it more than max, update max.

When we are done comparing,

2

One way can be:

perl -lane '$_>$m and $m=$_ for @Fprint $m' sample.txt

Explanation:

-n option will process your input file on a per line basis.

-e option will apply the Perl code following it, to every line of input read.

-a option will split each line as it is read into individual fields and store them in an array @F.

-l option will make RS=ORS="n"

for @F will loop over each field, the current field being held in $_.

We compare the current field with the maximum and in case it it more than max, update max.

When we are done comparing, we print what is held in max.

The N/As shall be treated as 0 in numeric context so won't affect the result, unless of course all numerics were negative to begin with.

shareprint $m' sample.txt

Explanation:

-n option will process your input file on a per line basis.

-e option will apply the Perl code following it, to every line of input read.

-a option will split each line as it is read into individual fields and store them in an array @F.

-l option will make RS=ORS="n"

for @F will loop over each field, the current field being held in $_.

We compare the current field with the maximum and in case it it more than max, update max.

When we are done comparing, { we print what is held in max.

The N/As shall be treated as 0 in numeric context so won't affect the result, unless of course all numerics were negative to begin with.

edited Feb 24 at 13:54

Cbhihe

4021618

answered Feb 24 at 2:39

Rakesh Sharma

342115

edited Feb 24 at 13:54

Cbhihe

4021618

edited Feb 24 at 13:54

Cbhihe

4021618

edited Feb 24 at 13:54

Cbhihe

4021618

answered Feb 24 at 2:39

Rakesh Sharma

342115

answered Feb 24 at 2:39

Rakesh Sharma

342115

answered Feb 24 at 2:39

Rakesh Sharma

342115

this is working fine. Can you explain how it works ?

– ayrton_senna
Feb 24 at 4:47

Done. Please check.

– Rakesh Sharma
Feb 24 at 5:22

add a comment |

this is working fine. Can you explain how it works ?

– ayrton_senna
Feb 24 at 4:47

Done. Please check.

– Rakesh Sharma
Feb 24 at 5:22

this is working fine. Can you explain how it works ?

– ayrton_senna
Feb 24 at 4:47

Done. Please check.

– Rakesh Sharma
Feb 24 at 5:22

add a comment |

0

I have done by below method
Command

awk 'print $0' o.txt | sed -r "s/s+/n/g"| sed '/^$/d'| sort | uniq| sed -n '/[0-9]/p'| awk 'BEGINsum=0;m=" "($1 >sum)sum=$1m=sumENDprint m'

Output

 awk 'print $0' o.txt | sed -r "s/s+/n/g"| sed '/^$/d'| sort | uniq| sed -n '/[0-9]/p'| awk 'BEGINsum=0;m=" "($1 >sum)sum=$1m=sumENDprint m'

output

1351.8

answered Feb 24 at 15:32

Praveen Kumar BS

1,6351311

add a comment |

0

I have done by below method
Command

awk 'print $0' o.txt | sed -r "s/s+/n/g"| sed '/^$/d'| sort | uniq| sed -n '/[0-9]/p'| awk 'BEGINsum=0;m=" "($1 >sum)sum=$1m=sumENDprint m'

Output

 awk 'print $0' o.txt | sed -r "s/s+/n/g"| sed '/^$/d'| sort | uniq| sed -n '/[0-9]/p'| awk 'BEGINsum=0;m=" "($1 >sum)sum=$1m=sumENDprint m'

output

1351.8

answered Feb 24 at 15:32

Praveen Kumar BS

1,6351311

add a comment |

0

I have done by below method
Command

awk 'print $0' o.txt | sed -r "s/s+/n/g"| sed '/^$/d'| sort | uniq| sed -n '/[0-9]/p'| awk 'BEGINsum=0;m=" "($1 >sum)sum=$1m=sumENDprint m'

Output

 awk 'print $0' o.txt | sed -r "s/s+/n/g"| sed '/^$/d'| sort | uniq| sed -n '/[0-9]/p'| awk 'BEGINsum=0;m=" "($1 >sum)sum=$1m=sumENDprint m'

output

1351.8

answered Feb 24 at 15:32

Praveen Kumar BS

1,6351311

I have done by below method
Command

awk 'print $0' o.txt | sed -r "s/s+/n/g"| sed '/^$/d'| sort | uniq| sed -n '/[0-9]/p'| awk 'BEGINsum=0;m=" "($1 >sum)sum=$1m=sumENDprint m'

Output

 awk 'print $0' o.txt | sed -r "s/s+/n/g"| sed '/^$/d'| sort | uniq| sed -n '/[0-9]/p'| awk 'BEGINsum=0;m=" "($1 >sum)sum=$1m=sumENDprint m'

output

1351.8

answered Feb 24 at 15:32

Praveen Kumar BS

1,6351311

answered Feb 24 at 15:32

Praveen Kumar BS

1,6351311

answered Feb 24 at 15:32

Praveen Kumar BS

1,6351311

answered Feb 24 at 15:32

Praveen Kumar BS

1,6351311

add a comment |

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score 2 · Accepted Answer

One way can be:

perl -lane '$_>$m and $m=$_ for @Fprint $m' sample.txt

Explanation:

-n option will process your input file on a per line basis.

-e option will apply the Perl code following it, to every line of input read.

-a option will split each line as it is read into individual fields and store them in an array @F.

-l option will make RS=ORS="n"

for @F will loop over each field, the current field being held in $_.

We compare the current field with the maximum and in case it it more than max, update max.

When we are done comparing,

Praveen Kumar BSPraveen Kumar BS 1,6351311 · Accepted Answer · 2019-02-24 15:32:39Z

I have done by below method
Command

awk 'print $0' o.txt | sed -r "s/s+/n/g"| sed '/^$/d'| sort | uniq| sed -n '/[0-9]/p'| awk 'BEGINsum=0;m=" "($1 >sum)sum=$1m=sumENDprint m'

Output

 awk 'print $0' o.txt | sed -r "s/s+/n/g"| sed '/^$/d'| sort | uniq| sed -n '/[0-9]/p'| awk 'BEGINsum=0;m=" "($1 >sum)sum=$1m=sumENDprint m'

output

1351.8

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