[Tutor] implementing a table data structure in python?
orion_val at 163.com
Tue Dec 21 16:49:32 CET 2004
First of all, welcome to tutor at python.org
I've done a little modification on Kent's code to make it more
sensible. Please try it.
Assuming the data file is 'mydata'
1 1 2 3 23 0.1
13 2 3 4 24 0.15
24 1 1 2 12 0.2
45 2 3 5 1 0.12
116 6 2 7 27 0.18
211 9 4 6 28 0.45
My python code:
datafile='mydata' #Your datafile
columns=[1,2,3,5] #Columns which you'd like to print
print "Can't open data file."
for line in list(f):
data=[data[i] for i in columns]
print 'Column index out of range.'
> Hello tutors,
> As i'm new to this mailing list so i shall introduce myself. My name
> is Maarten and except for some shell scripting I have little practical
> experience in programming (I'm a Linux/Solaris sys-admin). I've doing
> (mostly) reading about Python. But now trying, despite of my lack of
> talent for programming, to do write some stuff in Python (i don't call
> them programs yet;).
> So maybe a bit bold for a newbie to start posting a correction but i
> wanted the code to work:
> Kent Johnson wrote:
>> columns = [1,3,4] # Column numbers to show, 0-based
>> f = open('mydata.txt')
>> for line in f:
>> data = line.split() # Assuming your data is tab- or space-delimited
>> data = [ item for i, item in data if i in columns ] # Filter out
>> unwanted columns
>> print data # Output one row of text - put your formatting here
>> There are probably more efficient ways to extract the data but this
>> should get you started.
> guess Kent forgot one line after:
> data = line.split()
> adding next line after it:
> data = enumerate(data)
> makes it work for me.
> $ cat mydata.txt
> 1 1 2 3 23 0.1
> 13 2 3 4 24 0.15
> 24 1 1 2 12 0.2
> 45 2 3 5 1 0.12
> 116 6 2 7 27 0.18
> 211 9 4 6 28 0.45
> Please correct my correction if i'm wrong.
> Still got a question. This notation/syntax of the list:
> [ item for i, item in data if i in columns ]
> is quite new for me. Can someone point me to more examples of this use
> Or give me the name of it (it must have a name) so i can google it?
> Tutor maillist - Tutor at python.org
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