Read and count

[Val Krem]

Thank you very much for the help.

First I want count by city and year. 
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 called  "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 objects together 

City
Xc1  4
Yv2  5



Sent from my iPad 

> On Mar 10, 2016, at 3:11 AM, Jussi Piitulainen <jussi.piitulainen at helsinki.fi> wrote:
> 
> Val Krem writes:
> 
>> 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
>> fo=open("dat", "r+")
>> str = fo.read();
>> print "Read String is : ", str
>> 
>> fo.close()
> 
> 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).
> 
> from collections import Counter
> 
> # collections.Counter is a special dictionary type for just this
> counts = Counter()
> 
> # 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 = line.split()
>        # collections.Counter has default 0,
>        # key is a tuple (city, year), parentheses omitted here
>        counts[city, year] += 1
> 
> print("city")
> for city, year in sorted(counts): # iterate over keys
>    print(city.lower(), year, counts[city, year], sep = "\t")
> 
> # Alternatively:
> # for cy, n in sorted(counts.items()):
> #   city, year = cy
> #   print(city.lower(), year, n, sep = "\t")
> -- 
> https://mail.python.org/mailman/listinfo/python-list