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From: Val Krem <valkrem@yahoo.com>
Newsgroups: comp.lang.python
Subject: Re: Read and count
Date: Thu, 10 Mar 2016 11:09:23 -0600
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Message-ID: <mailman.141.1457629772.15725.python-list@python.org>
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Thank you very much for the help.

First I want count by city and year.=20
City year count
Xc1.    2001.  1
Xc1.    2002.  3
Yv1.     2001.  1
Yv2.    2002.  4
This worked fine !

Now I want to count by city only
City. Count
Xc1.   4
Yv2.  5

Then combine these two objects with the original data and send it to a file c=
alled  "detout" with these columns:

"City", " year ", "x ", "cycount ", "citycount"

Many thanks again






This worked fine. I tried to count only by city  and combine the three objec=
ts together=20

City
Xc1  4
Yv2  5



Sent from my iPad=20

> On Mar 10, 2016, at 3:11 AM, Jussi Piitulainen <jussi.piitulainen@helsinki=
.fi> wrote:
>=20
> Val Krem writes:
>=20
>> Hi all,
>>=20
>> 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.
>>=20
>>=20
>> The data set look like
>> city year  x=20
>>=20
>> XC1 2001  10
>> XC1   2001  20
>> XC1   2002   20
>> XC1   2002   10
>> XC1 2002   10
>>=20
>> Yv2 2001   10
>> Yv2 2002   20
>> Yv2 2002   20
>> Yv2 2002   10
>> Yv2 2002   10
>>=20
>> out put will be
>>=20
>> city
>> xc1  2001  2
>> xc1   2002  3
>> yv1  2001  1
>> yv2  2002  3
>>=20
>>=20
>> Below is my starting code
>> count=3D0
>> fo=3Dopen("dat", "r+")
>> str =3D fo.read();
>> print "Read String is : ", str
>>=20
>> fo.close()
>=20
> Below's some of the basics that you want to study. Also look up the csv
> module in Python's standard library. You will want to learn these things
> even if you end up using some sort of third-party data-frame library (I
> don't know those but they exist).
>=20
> from collections import Counter
>=20
> # collections.Counter is a special dictionary type for just this
> counts =3D Counter()
>=20
> # with statement ensures closing the file
> with open("dat") as fo:
>    # file object provides lines
>    next(fo) # skip header line
>    for line in fo:
>        # test requires non-empty string, but lines
>        # contain at least newline character so ok
>        if line.isspace(): continue
>        # .split() at whitespace, omits empty fields
>        city, year, x =3D line.split()
>        # collections.Counter has default 0,
>        # key is a tuple (city, year), parentheses omitted here
>        counts[city, year] +=3D 1
>=20
> print("city")
> for city, year in sorted(counts): # iterate over keys
>    print(city.lower(), year, counts[city, year], sep =3D "\t")
>=20
> # Alternatively:
> # for cy, n in sorted(counts.items()):
> #   city, year =3D cy
> #   print(city.lower(), year, n, sep =3D "\t")
> --=20
> https://mail.python.org/mailman/listinfo/python-list