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Finding standard deviation for all columns in a data file

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# 1  
Old 04-23-2012
Finding standard deviation for all columns in a data file

Hi All,

I want someone to modify the below script from this forum so that it can be used for all columns in the file( instead of only printing column 3 mean and standard deviation values). I don't know how to loop around all the columns.

awk '{ lines=FNR; arr[lines]=$3; sum+=$3}      END{ avg=sum/lines      sum=0;      for(i=1; i<=lines; i++)       	{ v=arr[i]-avg;       	  sum+= v*v       	}      printf("n=%d avg=%f  stddev=%f\n",             lines, avg, sqrt( sum/( lines - 1) ) ) } ' filename

Thanks a lot.

Last edited by Scrutinizer; 04-23-2012 at 06:12 AM.. Reason: code tags
# 2  
Old 04-23-2012
{ lines=FNR; arr[lines]=$3; sum+=$3}

for x=1 to nf {
lines++ ;
arr[lines]=$x; sum+=$x ;

ie. Instead of forcing to use the third field, loop through the number of fields using the builtin variable NF. Note that lines is incremented for each value read in.

Moderator's Comments:
Mod Comment Please use [code] tags instead of [quote] tags

Last edited by Scrutinizer; 04-23-2012 at 06:14 AM.. Reason: code tags
# 3  
Old 04-23-2012
I am getting syntax error.....

Hi Anantha,

I am getting syntax error after I modified the original script as below( by substituting your suggested portion of code).
Please correct the code so that it will run without any errors.

awk '{for x=1 to nf \
{lines++ ;arr[lines]=$x; sum+=$x ;}} \
END{ avg=sum/lines; sum=0; \    
 for(i=1; i<=lines; i++)  \
     	{ v=arr[i]-avg;  sum+= v*v }\
 printf("n=%d avg=%f  stddev=%f\n",lines, avg, sqrt( sum/( lines - 1) ) ) } ' filename

# 4  
Old 04-23-2012
Actually I posted the code so that you could try it out yourself.

What did you try? Post some test data and we will see.


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