Word substitution in file

Ruby
1

Hi,

Can anyone help me in that?
I just want to write the following function:

substitute(f,g,w,x)

where f and g are files and w and x are strings
That function substitutes all the ocurrences of w in the file f and
writes x to g

For example, if f is:
"
Hello folks or
old men
"

and w = “ol” and x=“ur”

then g is:

"
Hello furks or
urd men
"

Can anyone show me some code?
I thinked to pass file to string but I thinked it was not very fast.
Better directly

2

def substitute(f,g,w,x) sed s/#{w}/#{x}/g < #{f} > #{g} end

3

Jason N. wrote:

def substitute(f,g,w,x) sed s/#{w}/#{x}/g < #{f} > #{g} end

Thank you but I get this errors:

sh: -c: line 0: syntax error near unexpected token newline' sh: -c: line 0:sed s/ol/ur/g < #<File:0xb7c6cb38> >
#<File:0xb7c6cb10>’

What happens?

The code:
" f1 = File.open(“original.txt”)
f2 = File.open(“canviada.txt”)

def substitute(f,g,w,x)
sed s/#{w}/#{x}/g < #{f} > #{g}
end

substitute(f1,f2,“ol”,“ur”)
"

original file has
"
Hello folks or
old men
"
and canviada is empty

Thanks in advance,
Xan.

4

Xan Xann wrote:

Hi,

Can anyone help me in that?
I just want to write the following function:

substitute(f,g,w,x)

where f and g are files and w and x are strings
That function substitutes all the ocurrences of w in the file f and
writes x to g

substitute(source,dest,find,replace)
data = File.read(source)
result = data.gsub(/#{find}/,#{replace})
File.open(dest) { |f| f.write(result) } if data != result
end

I thinked to pass file to string but I thinked it was not very fast.
Better directly

Not necessarily. Putting a file’s contents into a string is the best way
to
carry out substitutions, especially when regular expressions are
involved.

If the files are large, one can write a line-by-line, therefore
streaming,
solution, from one file to another, but this also has limitations when
sophisticated regular expressions are required.

5

Paul L. wrote:

Paul L. wrote:

File.open(dest) { |f| f.write(result) } if data != result

s/File.open(dest)/File.open(dest,“w”)/

Also “not tested!”. That may seem obvious at this point.

It does not work!!!:
wiki.rb:10: parse error, unexpected kEND

6

Paul L. wrote:

File.open(dest) { |f| f.write(result) } if data != result

s/File.open(dest)/File.open(dest,“w”)/

Also “not tested!”. That may seem obvious at this point.

7

Xan Xann wrote:

Paul L. wrote:

/ …

Also “not tested!”. That may seem obvious at this point.

It does not work!!!:
wiki.rb:10: parse error, unexpected kEND

My original code was actually pseudo-code, unbeknownst to me. :slight_smile:

#!/usr/bin/ruby

def substitute(source,dest,find,replace)
data = File.read(source)
result = data.gsub(/#{find}/,replace)
File.open(dest,“w”) { |f| f.write(result) } if data != result
end

substitute(“temp.txt”,“result.txt”,“i”,“x”)

temp.txt = “This is a test line.”

result.txt = “Thxs xs a test lxne.”

Tested, which I should have done in the first place.

8

Paul L. wrote:

Xan Xann wrote:

Paul L. wrote:

/ …

Also “not tested!”. That may seem obvious at this point.

It does not work!!!:
wiki.rb:10: parse error, unexpected kEND

My original code was actually pseudo-code, unbeknownst to me. :slight_smile:

#!/usr/bin/ruby

def substitute(source,dest,find,replace)
data = File.read(source)
result = data.gsub(/#{find}/,replace)
File.open(dest,“w”) { |f| f.write(result) } if data != result
end

substitute(“temp.txt”,“result.txt”,“i”,“x”)

temp.txt = “This is a test line.”

result.txt = “Thxs xs a test lxne.”

Tested, which I should have done in the first place.

I get this error:

wiki.rb:7:in read': can't convert File into String (TypeError) from wiki.rb:7:insubstitute’
from wiki.rb:12

with code:

require ‘fileutils’

    f1 = File.open("original.txt")
    f2 = File.open("canviada.txt")

def substitute(source,dest,find,replace)
data = File.read(source)
result = data.gsub(/#{find}/,replace)
File.open(dest,“w”) { |f| f.write(result) } if data != result
end

substitute(f1,f2,“ol”,“ur”)

What happens?
Thanks,
Xan.

9

Paul L. wrote:

#!/usr/bin/ruby

def substitute(source,dest,find,replace)
data = File.read(source)
result = data.gsub(/#{find}/,replace)
File.open(dest,“w”) { |f| f.write(result) } if data != result
end

The equality test there is probably unnecessary.
What you could do for a bit lower a cost, if you
really want to avoid the possible write overhead:

Untested too

require ‘fileutils’

def FileUtils.s(source, dest, subs = {})
data = File.read source
search = /#{subs.keys.map {|k| Regexp.escape k}.join ‘|’}/
result = data.gsub(search) {|found| subs[found]}
File.open(dest, ‘w’) {|f| f.write result} if $& # Regex matched
end

FileUtils.s ‘src.txt’, ‘dest.txt’, ‘foo’ => ‘bar’

10

Eero S. wrote:

Paul L. wrote:

#!/usr/bin/ruby

def substitute(source,dest,find,replace)
data = File.read(source)
result = data.gsub(/#{find}/,replace)
File.open(dest,“w”) { |f| f.write(result) } if data != result
end

The equality test there is probably unnecessary.
What you could do for a bit lower a cost, if you
really want to avoid the possible write overhead:

Untested too

require ‘fileutils’

def FileUtils.s(source, dest, subs = {})
data = File.read source
search = /#{subs.keys.map {|k| Regexp.escape k}.join ‘|’}/
result = data.gsub(search) {|found| subs[found]}
File.open(dest, ‘w’) {|f| f.write result} if $& # Regex matched
end

FileUtils.s ‘src.txt’, ‘dest.txt’, ‘foo’ => ‘bar’

This WORKS!!! finally

Thank you very much
It seems it supports regexp expressions. Is it true?

Xan.

11

Xan Xann wrote:

Eero S. wrote:

Untested too

require ‘fileutils’

def FileUtils.s(source, dest, subs = {})
data = File.read source
search = /#{subs.keys.map {|k| Regexp.escape k}.join ‘|’}/
result = data.gsub(search) {|found| subs[found]}
File.open(dest, ‘w’) {|f| f.write result} if $& # Regex matched
end

FileUtils.s ‘src.txt’, ‘dest.txt’, ‘foo’ => ‘bar’

This WORKS!!! finally

Thank you very much
It seems it supports regexp expressions. Is it true?

It just substitutes strings with their counterparts
given as the Hash. Regular expression support would
be a bit more involved.

12

Eero S. wrote:

Xan Xann wrote:

Eero S. wrote:

Untested too

require ‘fileutils’

def FileUtils.s(source, dest, subs = {})
data = File.read source
search = /#{subs.keys.map {|k| Regexp.escape k}.join ‘|’}/
result = data.gsub(search) {|found| subs[found]}
File.open(dest, ‘w’) {|f| f.write result} if $& # Regex matched
end

FileUtils.s ‘src.txt’, ‘dest.txt’, ‘foo’ => ‘bar’

This WORKS!!! finally

Thank you very much
It seems it supports regexp expressions. Is it true?

It just substitutes strings with their counterparts
given as the Hash. Regular expression support would
be a bit more involved.

Well, thanks you very much for your help

Xan.

13

Paul L. wrote:

Xan Xann wrote:

/ …

temp.txt = “This is a test line.”

result = data.gsub(/#{find}/,replace)
File.open(dest,“w”) { |f| f.write(result) } if data != result
end

substitute(f1,f2,“ol”,“ur”)

What happens?

Here is my example call to ‘substitute’:

substitute(“temp.txt”,“result.txt”,“i”,“x”)

You can see that I use strings containing the names of the files.

Here is your example call to ‘substitute’:

f1 = File.open(“original.txt”)
f2 = File.open(“canviada.txt”)

substitute(f1,f2,“ol”,“ur”)

You are using open file handles instead of strings. The remedy is,
instead
of using your example of my example, use my example.

Yes, sorry. What stupid error!!!

Thanks,
Xan.

14

Xan Xann wrote:

/ …

temp.txt = “This is a test line.”

result = data.gsub(/#{find}/,replace)
File.open(dest,“w”) { |f| f.write(result) } if data != result
end

substitute(f1,f2,“ol”,“ur”)

What happens?

Here is my example call to ‘substitute’:

substitute(“temp.txt”,“result.txt”,“i”,“x”)

You can see that I use strings containing the names of the files.

Here is your example call to ‘substitute’:

f1 = File.open(“original.txt”)
f2 = File.open(“canviada.txt”)

substitute(f1,f2,“ol”,“ur”)

You are using open file handles instead of strings. The remedy is,
instead
of using your example of my example, use my example.