[Tutor] implementing a table data structure in python?
maarten at dds.nl
Tue Dec 21 15:27:13 CET 2004
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?
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