[Numpy-discussion] NOOB Alert: Looping Through Text Files...

dstaley dstaley at usgs.gov
Fri Jan 14 17:52:45 EST 2011

Warning, I am a python noob.  Not only do I not know python, I really don't
know anything about programming outside of ArcInfo and the ancient AML
language.  Regardless, here is my problem....

Let's say I have three text files (test1.txt, test2.txt and test3.txt). 
Each text file has 1 line of text in it "This is my text file", to which I
want to add (append) a new line of text saying "I suck at Python and need
help", and then save the file with a suffix attached (eg test1_modified.txt,
test2_modified.txt, test3_modified.txt).  

I guess this is the equivalent of making a change in MS Word and using the
"Save As..." command to maintain the integrity of the original file, and
save the changes in a new file.  But, I want to also do that in a loop (this
is a simplified example of something I want to do with hundreds of text

Now, I understand how to add this line to an existing text file:

text_file = open("test1.txt", "a")
text_file.write("\nI suck at Python and need help")

While this adds a line of text, it saves the change to the original file
(does not add the _modified.txt suffix to the file name), nor does it allow
me to loop through all three of the files.

I'm sure this is an easy thing to do, and is online in a million places. 
Unfortunately, I just cannot seem to find the answer.  Here is my thought

First i would define the list from which I would loop:

textlist = ["test1.txt", "test2.txt", "test3.txt"]

for i in textlist:
	text_file = open(textlist, "a")
	text_file.write("\nI suck at Python and need help")

But, this doesn't work.  It gives me the error:

coercing to Unicode: need string or buffer, list found

SO, I guess I need to do this from something other than a list?

Even if it did work, it does not suit my needs as it does not create a new
file and does not allow me to add the _modified.txt suffix, which will allow
me to keep the original file intact.

>From a responses to a previous post, this seems as if it may have something
to do with a python dictionary, but I'm not sure.

I'm probably totally off on how this should even be written, so any advice
or suggestions would be greatly appreciated.  

Thanks in advance for your help!


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