CODEWITHSUNDEEP
regexawksedcommand-linegrep
Ahmed
Ahmed

Reputation: 23

Print only the lines that contain three sequential consecutive numbers

I'm filtering a text file with numbers and names I want to print only the lines that contain sets of three sequential consecutive digits. The input list:

123 321 567 765 124 5689 12345.

The output should contain:

123 321 567 765 12345

I have tried this command 

awk ' {split ("", N) # delete array N 
L = 1 # initialize boolean L to TRUE
for (i=1; i<=length($1); i++){ # for each digit
    P = substr($1, i, 1) 
    if (N[P-1] || N[P+1]){ # if contiguous digit exists, 
        L = 0 break # set L to FALSE; and quit the for loop 
    } N[P] = 1 } } L ' file

but it is not working as intended.

I like any sed or grep or awk command to work with.

Upvotes: 2

Views: 768

Answers (2)

user557597
user557597

Reputation:

This is the basic regex for 3 sequential (ascending or descending) numbers.

(?:012|123|234|345|456|567|678|789)|(?:987|876|765|654|543|432|321|210)

https://regex101.com/r/hd5PzR/1

You can decorate it with \d*(?:(?:012|123|234|345|456|567|678|789)|(?:987|876|765|654|543|432|321|210))\d*
if needed.

https://regex101.com/r/hd5PzR/2

Upvotes: 2

Kyle Banerjee
Kyle Banerjee

Reputation: 2794

Are you looking for help on homework or are you trying to solve a problem? If the latter is the case, using an algorithmic approach when there are so few combinations is like using a chain saw to cut butter. Consider the following script:

mystring="012 123 234 567 678 789"
revstring=$(echo $mystring|rev)
checkstring="$mystring $revstring"

for checkno in $(echo $checkstring);
do
        grep $checkno numbers
done

Note that this will get you duplicate output for lines containing more than one sequence, but just run that through |sort -u to eliminate them.

Upvotes: 0

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