How to insert random numbers into each line? Post: 302973924

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Top Forums Shell Programming and Scripting How to insert random numbers into each line? Post 302973924 by Don Cragun on Tuesday 24th of May 2016 04:57:15 AM

05-24-2016

Registered User

Hi roof,
Why don't you think 000 and 029 just as valid as 3-digit random numbers as 100 and 999?

Assuming that characters two through four on every input line are spaces (which was not stated in the requirements, but is true in the given 2-line sample input) and you're using a recent bash, a 1993 or later ksh, or zsh, you could change your suggestion from:

Code:

echo ${line:s/    / $((RANDOM%1000))}

to:

Code:

echo ${line:s/    / $((RANDOM%10))$((RANDOM%10))$((RANDOM%10))}

to change characters three through five to a 3-digit random number in the given sample input.

But, hhdzhu still hasn't given us a clear specification of what output is desired. (Specifying offsets 2 to 4 are to be changed is ambiguous since we haven't been told whether the 1st character on a line is offset 0 (as in bash and recent ksh ${variable:offset[:length]}) or offset 1 (as in awk substr(string, offset[, length])) and sample input and output that does' t match either of these.

And, since the input is "thousands of lines", it isn't obvious whether or not my awk suggestion would be slower or faster processing the desired file than the zsh (or ksh93 or bash) script you suggested (modified as shown above) inserted into a while read loop to process the entire file instead of just one line.

Don Cragun

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clarnv

clarnv.f(3)							      LAPACK							       clarnv.f(3)

NAME

       clarnv.f -

SYNOPSIS

   Functions/Subroutines
       subroutine clarnv (IDIST, ISEED, N, X)
	   CLARNV

Function/Subroutine Documentation
   subroutine clarnv (integerIDIST, integer, dimension( 4 )ISEED, integerN, complex, dimension( * )X)
       CLARNV

       Purpose:

	    CLARNV returns a vector of n random complex numbers from a uniform or
	    normal distribution.

       Parameters:
	   IDIST

		     IDIST is INTEGER
		     Specifies the distribution of the random numbers:
		     = 1:  real and imaginary parts each uniform (0,1)
		     = 2:  real and imaginary parts each uniform (-1,1)
		     = 3:  real and imaginary parts each normal (0,1)
		     = 4:  uniformly distributed on the disc abs(z) < 1
		     = 5:  uniformly distributed on the circle abs(z) = 1

	   ISEED

		     ISEED is INTEGER array, dimension (4)
		     On entry, the seed of the random number generator; the array
		     elements must be between 0 and 4095, and ISEED(4) must be
		     odd.
		     On exit, the seed is updated.

	   N

		     N is INTEGER
		     The number of random numbers to be generated.

	   X

		     X is COMPLEX array, dimension (N)
		     The generated random numbers.

       Author:
	   Univ. of Tennessee

	   Univ. of California Berkeley

	   Univ. of Colorado Denver

	   NAG Ltd.

       Date:
	   November 2011

       Further Details:

	     This routine calls the auxiliary routine SLARUV to generate random
	     real numbers from a uniform (0,1) distribution, in batches of up to
	     128 using vectorisable code. The Box-Muller method is used to
	     transform numbers from a uniform to a normal distribution.

       Definition at line 100 of file clarnv.f.

Author
       Generated automatically by Doxygen for LAPACK from the source code.

Version 3.4.1							  Sun May 26 2013						       clarnv.f(3)