如何将值附加到python字典并在函数调用中返回

Question

I have a for loop within a python function call that executes a number of times. I need to return the values in a dictionary to dump them into a db.

Here is a piece of sample code, how can I append values to a dictionary and ensure I have all of them for further use.

def parser_code():
    log = dict()
    for i in range(len):
        log['abc'] = 2*i
        log['xyz'] = 10+i
    return log

This will execute atleast twice so I want a dictionary to be log = {['abc':2, 'xyz':11],['abc':3, 'xyz':12]}

How can I append to the result each time? Or is there a smarter way to do this?

Answer 1

I think you are looking for defaultdict part of std-libs.

from collections import defaultdict
glog = defaultdict(list)
def parser_code(dd):
    for i in range(length):
        dd['abc'].append(2*i)
    return dd

glog = parser_code(glog)

if you actually want to use your result you have to have make sure that the dict is not created new for every call to your function.

still a bit unclear if you need a dict or not, you will only need that if you want the ability for key-lookup. If you are happy with just making a list (array) of numbers, then go ahead and use a list.

glog = list()
def parser_code(lst):
    return lst + [2*i for i in range(length)]
glog = parser_code(glog)

Answer 2

I'm not 100% sure what behavior you're expecting, but I think this code should suffice:

def parser_code(length):
  log = list()
  for i in range(length):
    this_dict = dict()
    this_dict['abc'] = 2*i
    this_dict['xyz'] = 10+i
    log.append(this_dict)
  return log

Answer 3

you can give the dictionary as a parameter to your function.

please not that your code is not working for me (original indention of the for loop - it's corrected now) and the len parameter). I needed to guess a little bit what you are actually doing. Could you take a look at your example code in the question or comment here?

def parser_code(result, length):
   for i in range(length):
       result['abc'] = 2*i
       result['xyz'] = 10+i
   return result

d = {}
parser_code(d, 3)
print(d)
parser_code(d, 3)
print(d)

will give this output:

python3 ./main.py 
{'abc': 4, 'xyz': 12}
{'abc': 4, 'xyz': 12}