In a file, replace blank line by the last line not blank above
Dear All,
In a CSV file, say that a given column has been extracted. In that column, information is missing (i.e. blank lines appear). I would like to replace the blank lines by the last valid line (not blank) previously read.
For example, consider the extract below:
Code:
123
234
543
111
234
198
I would like this extract to be replaced by:
Code:
123
234
234
543
543
543
111
234
234
234
198
198
I wrote a simple script to do the job that reads myfile.txt and writes the result in out.txt:
Code:
MEMVAL=""
LINENUM=0
while read LINE
do
LINENUM=$(($LINENUM+1));
# Test if the line is blank
CURLINE=`echo $LINE | grep -E '^[:space]*$'`
TEST="$?"
if [ $TEST == 0 ]; then
if [ $LINENUM == 1 ]; then # The first line cannot be blank!!
exit 1
else
# Replace current blank line by memorised info in the output data file
echo "$MEMVAL" >> out.txt
fi
else
MEMVAL="$LINE"
# At first init output data file
if [ $LINENUM == 1 ]; then
echo "$LINE" > out.txt
fi
fi
done < myfile.txt
This script does the job, but it takes ages.
Also I guess there are far more efficient ways to do this by using either sed of awk (maybe csvfix in my case).
Would anybody have a suggestion?
Cheers, Bagvian
Moderator's Comments:
Please use CODE tags as required by forum rules!
Last edited by RudiC; 02-24-2017 at 03:56 PM..
Reason: Added CODE tags.
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Hi
I nned cmd to which will help me to replace a line in file with blank line
e.g.
file1
a
b
c
d
e
after running cmd I shud get
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b
c
d
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FBB::lm(3bobcat) OFoldStream manipulator FBB::lm(3bobcat)NAME
FBB::lm - Manipulator setting left margins of OFoldStream objects
SYNOPSIS
#include <bobcat/ofoldstream> or
#include <bobcat/ofoldstreambuf>
Linking option: -lbobcat
DESCRIPTION
The lm class implements a manipulator that can be inserted into OFoldStream objects to set the stream's left margin to a requested value.
Depending on the tab-setting of the OFoldStream the inserted value represents the number of blank space characters or the number of
tab-characters that will be used for the left margin.
The request will be processed at the next newline character or std::flush or std::endl manipulator that is inserted into the stream. If a
line is still once an lm object and a flush manipulator are inserted into the stream then the new left margin will be effective at the next
word inserted into that line (cf., the example section below).
A bad_cast exception is thrown when the manipulator is inserted into an ostream that is not using a OFoldStreambuf buffer.
NAMESPACE
FBB
All constructors, members, operators and manipulators, mentioned in this man-page, are defined in the namespace FBB.
INHERITS FROM -
CONSTRUCTOR
o lm(size_t newValue):
The standard copy constructor is available.
MEMBER FUNCTIONS
There are no public or protected member functions in this class.
EXAMPLE
#include <iostream>
#include <bobcat/ofoldstream>
using namespace std;
using namespace FBB;
int main()
{
OFoldStream out(cout, 0, 80);
out << "hello world (left margin is 0)" << lm(4) << "
"
"this uses a 4 character wide left margin
" <<
lm(0) << flush << "at column 0 again
";
return 0;
}
FILES
bobcat/lm - defines the class interface
SEE ALSO bobcat(7), manipulators(3bobcat), mlm(3bobcat), ofoldstream(3bobcat)BUGS
None Reported.
DISTRIBUTION FILES
o bobcat_3.01.00-x.dsc: detached signature;
o bobcat_3.01.00-x.tar.gz: source archive;
o bobcat_3.01.00-x_i386.changes: change log;
o libbobcat1_3.01.00-x_*.deb: debian package holding the libraries;
o libbobcat1-dev_3.01.00-x_*.deb: debian package holding the libraries, headers and manual pages;
o http://sourceforge.net/projects/bobcat: public archive location;
BOBCAT
Bobcat is an acronym of `Brokken's Own Base Classes And Templates'.
COPYRIGHT
This is free software, distributed under the terms of the GNU General Public License (GPL).
AUTHOR
Frank B. Brokken (f.b.brokken@rug.nl).
libbobcat1-dev_3.01.00-x.tar.gz 2005-2012 FBB::lm(3bobcat)
02-24-2017
