Hello and welcome.
Please see my comments below.
On 09/03/2016 21:30, Val Krem via Python-list wrote:
Hi all,
I am a new learner about python (moving from R to python) and trying read and
count the number of observation by year for each city.
The data set look like
city year x
XC1 2001 10
XC1 2001 20
XC1 2002 20
XC1 2002 10
XC1 2002 10
Yv2 2001 10
Yv2 2002 20
Yv2 2002 20
Yv2 2002 10
Yv2 2002 10
out put will be
city
xc1 2001 2
xc1 2002 3
yv1 2001 1
yv2 2002 3
Below is my starting code
count=0
Seems like you'd want a counter here
https://docs.python.org/3/library/collections.html#collections.Counter.
You'll need to know how to import this so start here
https://docs.python.org/3/tutorial/modules.html
fo=open("dat", "r+")
We'd normally use the 'with' keyword here so the file automatically gets
closed so:-
with open("dat", "r+") as fo:
str = fo.read();
'str' isn't a good name as it overrides the builtin function of that
name. This will read the entire file. Easiest to loop as in:-
for line in fo.readlines():
Now you'll need a split call to get at your data
https://docs.python.org/3/library/stdtypes.html#str.split and update
your counter. Once this loop is finished use another loop to produce
your output with print.
print "Read String is : ", str
The above is for Python 2, it needs parenthesis for Python 3. I'd
recommend starting with the latter if that's possible.
fo.close()
Not needed if you use the 'with' keyword as discussed above.
Many thanks
No problem as I'm leaving you to put it all together :)
--
My fellow Pythonistas, ask not what our language can do for you, ask
what you can do for our language.
Mark Lawrence
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https://mail.python.org/mailman/listinfo/python-list
