Using python as a search and replace macro; how to implement an unknown value

[nihilium]

I've searched a bit for this, but haven't stumbled upon anything that is useful for me yet. My question is pretty simple; I have the following script:

inputFile = file('C:/Documents and Settings/example.txt', 'r')
data = inputFile.read( )
inputFile.close ()
data = data.replace('t his x something', 'that x something else')
outputFile = file ('C:/Documents and Settings/example.txt', 'w')
outputFile.writ e(data)
outputFile.clos e()

Where x is an unknown decimal typically with three digits (e.g. 145.531) whose exact value is not predictable.

How do I implement x?


Thanks in advance.

[bvdet]

I've searched a bit for this, but haven't stumbled upon anything that is useful for me yet. My question is pretty simple; I have the following script:
[code=Python]
inputFile = file('C:/Documents and Settings/example.txt', 'r')
data = inputFile.read( )
inputFile.close ()
data = data.replace('t his x something', 'that x something else')
outputFile = file ('C:/Documents and Settings/example.txt', 'w')
outputFile.writ e(data)
outputFile.clos e()[/code]

Where x is an unknown decimal typically with three digits (e.g. 145.531) whose exact value is not predictable.

How do I implement x?


Thanks in advance.

Please use code tags in your posts. You code will generally be much more readable.

You can use string formatting to accomplish your goal.[code=Python]
>>> data = 'The data contains "this 345.543 something" which needs to be replaced.'
>>> x = 345.54321
>>> data.replace('t his %.3f something' % x, 'that %.3f something else' % x)
'The data contains "that 345.543 something else" which needs to be replaced.'
>>> [/code]If you do not know what x is beforehand:[code=Python]import re
patt = re.compile(r'th is (\d+\.\d+) something')
data = 'The data contains "this 0.56658 something" which needs to be replaced.'
m = patt.search(dat a)
if m:
data1 = data.replace(m. group(0), 'that %s something else' % m.group(1))

>>> data
'The data contains "this 0.56658 something" which needs to be replaced.'
>>> data1
'The data contains "that 0.56658 something else" which needs to be replaced.'
>>> [/code]

[nihilium]

>>> [/code]If you do not know what x is beforehand:[code=Python]import re
patt = re.compile(r'th is (\d+\.\d+) something')
data = 'The data contains "this 0.56658 something" which needs to be replaced.'
m = patt.search(dat a)
if m:
data1 = data.replace(m. group(0), 'that %s something else' % m.group(1))

>>> data
'The data contains "this 0.56658 something" which needs to be replaced.'
>>> data1
'The data contains "that 0.56658 something else" which needs to be replaced.'
>>> [/code]

Ok, thanks for the help so far. I'm not so familiar with Python, so I didn't quite get how to use the script.

Let's say that the text that needs to be replaced is in the document C:/Documents and Settings/example.txt, so I want to replace the text in that document as an automated process by running this script. For example I want to translate English dates into another language: December 2 should become 2. desember, where the number is a wildcard.

[woooee]

It was embedded in the code submitted by bvdet.
x=2 ## the unknown date
string_to_find= "December %d" % (x)
print "The string to find is", string_to_find

This is called string formatting. Here is link to the "Dive Into Python" page on string formatting http://www.diveintopyt hon.org/native_data_typ es/formatting_stri ngs.html

[nihilium]

[code=Python]import re
patt = re.compile(r'th is (\d+\.\d+) something')
data = 'The data contains "this 0.56658 something" which needs to be replaced.'
m = patt.search(dat a)
if m:
data1 = data.replace(m. group(0), 'that %s something else' % m.group(1))

>>> data
'The data contains "this 0.56658 something" which needs to be replaced.'
>>> data1
'The data contains "that 0.56658 something else" which needs to be replaced.'
>>> [/code]

I finally understood this script, and it turns out it's just what I was looking for. Thanks!