replacing multiple lines with multiple lines in ascii file

2011 5 9
3 个回答
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0 个投票

Hi
I would like to make a routine that can replace multiple lines with other multiple lines in a ascii file. This could for example be to replace 7 lines with 4 lines. I can not do it one line at the time because the single lines of the 7 lines are present other places in the file than in the 7 lines.
For single line replacement I have used
fin = fopen('in.txt','r');
fout = fopen('out.txt', 'w+');
while ~feof(fin)
s = fgetl(fin);
s = strrep(s, 'old string', 'newstring');
fprintf(fout,'%s\n',s);
end
fclose(fin);
fclose(fout);
But I can't figure out an easy way to convert this to handle multiple lines replacement.
Do you have any ideas?
Thanks in advance.
Regards Brian.

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 采纳的回答

Jarrod Rivituso
Jarrod Rivituso 2011-5-9

1 个投票

Can you read the whole file in and then just replace the strings?
wholeFile = fileread('myFile.txt');
newStr = 'This is the replacement for line 2 and 3';
oldStr = ['This is line 2' char(13) char(10) 'This is line 3'];
newFileData = strrep(wholeFile,oldStr,newStr);
fileID = fopen('newFile.txt','w')
fprintf(fileID,'%s',newFileData);
fclose(fileID)
Note that char(10) and char(13) are just line breaks and carriage returns.

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Brian Bak
Brian Bak 2011-5-9
Hi Jarrod
Thank you that works.
I am trying to construct the newStr and oldStr variables from two text documents (original.txt and replace.txt) that contains several newStr and oldStr separated by a blank line.
original = fopen('original.txt','r');
replace = fopen('replace.txt','r');
wholeFile = fileread('wholeFile.txt');
NL = [char(13) char(10)]; % New line
s = '';
i = 1;
while ~feof(original)
j = 1;
while strcmp(s,' ') ~= 1
if j==1
s = fgetl(original);
org{i,1} = [s NL];
j=0;
else
s = fgetl(original);
org{i,1} = [org{i,1} s NL];
end
end
i = i+1;
s = '1';
end
Where
original.txt:
-----------------
first lines t
o be replaced
second lines
to be replaced
-----------------
replace.txt:
-----------------
first lines t
hat are repla
cing
second lines
that are repl
acing
-----------------
The strings for replace called rep are created in a similar way. The code makes one long string of every block that is separated by blank lines. For some reason it does not work when I try to use these strings in the string replace function strcmp.
fileID = fopen('newfile.txt','w');
for i = 1:length(rep)
newStr = rep{i};
oldStr = org{i};
if i == 1
newFileData = strrep(wholeFile,oldStr,newStr);
else
newFileData = strrep(newFileData,oldStr,newStr);
end
end
fprintf(fileID,'%s',newFileData);
fclose(fileID);
I think it is the way I construct the oldStr and newstr. Do you have any suggestions?
Thanks in advance
Jarrod Rivituso
Jarrod Rivituso 2011-5-9
Two thoughts
- strfind is helpful for finding strings. though, you may find even more use if you just again read the entire files in and then split them using regexp...
>> str = 'this is something, which is separated, by some commas'
>> regexp(str,',','split')
- When debugging stuff like this, i find it very useful to convert things to numeric and display their ascii values on the command prompt from time to time
>> str = sprintf('this is something \n which is separated \r\n by carriage returns and new lines')
>> double(str)

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更多回答（2 个）

Ken Atwell
Ken Atwell 2011-5-11

0 个投票

Have you considered regular expressions? the MATLAB function regexprep would probably do the trick:
old_str = [];
rep_str = [];
for i = 1:5
old_str = [ old_str sprintf('Old Line %d\n', i) ];
end
for i = 2:3
rep_str = [ rep_str sprintf('New Line %d\n', i) ];
end
new_str = regexprep(old_str, 'Old Line 2\W+Old Line 3\W+', rep_str);
The '\W+' is a bit of regular expression magic to match one or more whitespace characters, which is why it can span multiple lines.
Brian Bak
Brian Bak 2011-5-12

0 个投票

Hi
Thank you for your answers. I got it to work now.
clc;clear all;
original = fopen('original.txt','r'); % text blocks separated by empty line with one blank space
replace = fopen('replace.txt','r');% text blocks separated by empty line with one blank space
wholeFile = fileread('OLD_file.txt');
NL = [char(13) char(10)]; % New line
s = '';
i = 1;
while ~feof(original)
j = 1;
while strcmp(s,' ') ~= 1
if j==1
s = fgetl(original);
org{i,1} = [s NL];
j=0;
else
s = fgetl(original);
if strcmp(s,' ') ~= 1
org{i,1} = [org{i,1} s NL];
end
end
end
i = i+1;
s = '1';
end
s = '';
i = 1;
while ~feof(replace)
j = 1;
while strcmp(s,' ') ~= 1
if j==1
s = fgetl(replace);
rep{i,1} = [s NL];
j=0;
else
s = fgetl(replace);
if strcmp(s,' ') ~= 1
rep{i,1} = [rep{i,1} s NL];
end
end
end
i = i+1;
s = '1';
end
fileID = fopen('NEWfile.txt','w');
for i = 1:length(rep)
newStr = rep{i};
oldStr = org{i};
if i == 1
newFileData = regexprep(wholeFile, oldStr, newStr,'once','ignorecase'); %strrep(wholeFile,oldStr,newStr);
else
newFileData = regexprep(newFileData, oldStr, newStr,'once','ignorecase'); %strrep(newFileData,oldStr,newStr);
end
end
fprintf(fileID,'%s',newFileData);
fclose(fileID);
Best regards Brian

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