Thread: rearrangement of columns in data file

HI i am new to c programming and my area is research mainly. I am attaching here two files 1. forum_new.txt 2. forum_old.txt
Forum_old.txt is the file i am getting from software package and forum_new.txt is the file i require to analyze the data. This time i done it manually as size of fiel is small. If there is any program that can convert automatically Forum_old.txt to forum_new.txt.
basically this is re-arrangement of columns
the first column is repeated after 10 values.

It will be very halpful to me if i get any kind of help.

thanks for your reply but could you please answer in C language

Since you can do it manually, maybe try to imagine a new 2D array in your head, try to notice how the notepad page could match up to the array in your head, and work out the steps.

This is not a good problem for C. Something like perl or awk is better suited. Here's some awk:

Code:

awk 'NF==2 {a[$1]=a[$1]"\t"$2}; END {for(x in a) print x,a[x]}' FORUMS_OLD.txt  | sort -n

(Beware anyone playing with the given data: it has the windows line endings. (dos2unix can fix that.))

In C, the problem is matching up the first column numbers. A linear search is good enough for the data you've shown, but if the real data has more 1st-column values, then a binary search may be better. Both the perl and awk solutions use hash tables for the purpose. Incidentally, they also treat all the numbers as strings, which is a good way to perfectly preserve the input values (instead of converting them to an internal floating-point format and back to an output string again).

A C solution is very ugly compared to the perl and awk solutions. And to write it in full generality (making it equivalent to the perl and awk solutions) would be somewhat painful.

That's a good idea since the key fields are spread out in the original data. Bringing them together really simplifies things.

There's another possibility if we're allowed to assume that the same key fields appear in the same order in each group, and each group is separated by a blank line (which is the case in the given data).

Code:

char table[MAX_ROWS][MAX_LINE]

row = 0
loop:
  read a line
  if the line is blank
    break
  else
    strcpy(table[row++], line)

row = 0
loop:
  read a line
  if EOF
    break
  else if line is blank
    row = 0
    continue
  else
    strcat(table[row], "\t")
    strcat(table[row++], second field of line)

print out the table

You could add a check to ensure that (for all groups after the first) the first field of the input line matched the first field in the current table element (fatal error, otherwise).

That's probably the simplest solution, but only because it makes the most assumptions.