Aggregating key value pair in python

Question

I have a question related to python code. I need to aggregate if the key = kv1, how can I do that?

input='num=123-456-7890&kv=1&kv2=12&kv3=0'
result={}
for pair in input.split('&'):
(key,value) = pair.split('=')
if key in 'kv1':
   print value
   result[key] += int(value)
print result['kv1']

Thanks a lot!!

Answer 1

I'm assuming you meant key == 'kv1' and also the kv within input was meant to be kv1 and that result is an empty dict that doesn't need result[key] += int(value) just result[key] = int(value)

input = 'num=123-456-7890&kv1=1&kv2=12&kv3=0'
keys = {k: v for k, v in [i.split('=') for i in input.split('&')]}

print keys # {'num': '123-456-7890', 'kv2': '12', 'kv1': '1', 'kv3': '0'}

result = {}
for key, value in keys.items():
    if key == 'kv1':

        # if you need to increase result['kv1']
        _value = result[key] + int(value) if key in result else int(value)
        result[key] = _value

        # if you need to set result['kv1']
        result[key] = int(value)

print result # {'kv1': 1}

Assuming you have multiple lines with data like:

num=123-456-7890&kv1=2&kv2=12&kv3=0
num=123-456-7891&kv1=1&kv2=12&kv3=0
num=123-456-7892&kv1=4&kv2=12&kv3=0

Reading line-by-line in a file:

def get_key(data, key):
    keys = {k: v for k, v in [i.split('=') for i in data.split('&')]}
    for k, v in keys.items():
        if k == key: return int(v)
    return None

results = []

for line in [line.strip() for line in open('filename', 'r')]:
    value = get_key(line, 'kv1')
    if value:
        results.append({'kv1': value})

print results # could be [{'kv1': 2}, {'kv1': 1}, {'kv1': 4}] 

Or just one string:

with open('filename', 'r') as f: data = f.read()

keys = {k: v for k, v in [i.split('=') for i in data.split('&')]}

result = {}
for key, value in keys.items():
    if key == 'kv1':
        result[key] = int(value)

Console i/o:

c:\nathan\python\bnutils>python
Python 2.7.5 (default, May 15 2013, 22:44:16) [MSC v.1500 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> def get_key(data, key):
...     keys = {k: v for k, v in [i.split('=') for i in data.split('&')]}
...     for k, v in keys.items():
...         if k == key: return int(v)
...     return None
...
>>> results = []
>>> for line in [line.strip() for line in open('test.txt', 'r')]:
...     value = get_key(line, 'kv1')
...     if value:
...         results.append({'kv1': value})
...
>>> print results
[{'kv1': 2}, {'kv1': 1}, {'kv1': 4}]
>>>

test.txt:

num=123-456-7890&kv1=2&kv2=12&kv3=0
num=123-456-7891&kv1=1&kv2=12&kv3=0
num=123-456-7892&kv1=4&kv2=12&kv3=0

Answer 2

import urlparse
urlparse.parse_qs(input)

results in: {'num': ['123-456-7890'], 'kv2': ['12'], 'kv': ['1'], 'kv3': ['0']}

The keys are aggregated for you.

Answer 3

You could do it this way, so basically just add an extra if else block dealing with the empty case for key

input='num=123-456-7890&kv=1&kv2=12&kv3=0'
result={}
for pair in input.split('&'):
    temp = pair.split('=')
    key = temp[0]
    value = [1]
    if key in 'kv1':
        if key in p:
             print value //do you really want to output this?
             result[key] += int(value)
        else:
             print value //do you really want to output this?
             result[key] = int(value)
print result['kv1']