[Tutor] a quick Q: how to use for loop to read a series of files with .doc end

[lina]

On Fri, Sep 30, 2011 at 12:31 AM, Walter Prins <wprins at gmail.com> wrote:

> Hi,
>
> On 29 September 2011 17:07, lina <lina.lastname at gmail.com> wrote:
>
>> I found one thing a bit weird, Here is the one:
>>
>> import os.path
>>
>> tokens=['E']
>> result=[]
>>
>> """
>> for fileName in os.listdir("."):
>>     if os.path.isfile(fileName) and os.path.splitext(fileName)[1]==".xpm":
>> """
>> filedata = open("1.xpm")
>> text=filedata.readlines()
>> for line in text[23]:
>>     print line
>>
>
>> 1] $ python try2.py | wc -l
>> 206
>>
>
> Please go and carefully study how strings, lists etc work -- you don't seem
> to grasp what "text[23]" returns vs what text[23:24] etc returns etc.  To
> spell it out:  If the variable text refers to a list of strings, then
> text[23] is the 24th string.  24th, because the index starts from 0.
> text[23:24] by contrast, is a sublist (called a slice) that contains strings
> 24 and 25 from the original list.
>
> So, if text[23] is already itself a single string, what can the following
> code possibly mean?  Eg in general, what does s[0] give you if s is a
> string?  A: The first character in s. So then, what does the following do:
>
> for x in text[23]:
>   print x
>
> a: It steps through the letters in text[23] and prints each in turn (on a
> new line.)
>
> So what you then do when you "wc -l" text[23], is to effectively count the
> number of characters in line 24....
>
> You should probably just have run the script without the wc -l and this
> would've become very clear very quickly on inspecting the output.   ;)
>
> The other results are similarly explainable, by examining the output. (To
> be exact, the lines in the sublists/slices include newline characters.  When
> you print them seperately, you therefore end up with more lines than you
> think.  Try "print line.strip()" to get rid of the newline.  Try the
> following in the python interpreter:
>
> f=open('C:\\Users\\walterp\\Desktop\\1.xpm')
> >>> lines=f.readlines()
> >>> slice1=lines[23]
> >>> slice2=lines[23:24]
> >>> slice3=lines[23:25]
> >>> print slice1
> >>> print slice2
> >>> print slice3
> >>> print len(slice3)
>

Thanks, I truly understand now. There was a "blank line", and the strip()
works.

(I learned C 10 years ago, but barely used. so can understand something very
basic. Thanks again for your explaination)

Now I am facing how to read each column about the occurence of some letter.

Long time ago, my senior left me a script with the following line,

for line in text:
    result.append({t:line.count(t) for t in tokens})

for index,r in enumerate(result):
    print(index,"-----",r)

I don't understand how it works, kinda of transpose a matrix?




> etc.
>
>
> Walter
>
>
>
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-- 
Best Regards,

lina
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