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title: 'Python Append Key'
date: '2021-12-04T10:02:02-05:00'
status: publish
permalink: /python-append-key
author: admin
excerpt: ''
type: post
id: xxxx
category:
    - 'python'
tag: ['python','dict']
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Python Append Key

Building a dict and ordering it into groups by key is sometimes very useful.

Teh following code show using the if .. in option and defaultdict option of checkign for a key when loading the dictionary. Although people warn that using has_key or if .. in type checks slows it down a lot my timings was fairly similar. I left some commented code in for my own reference.

source

from collections import defaultdict
from time import time

sample_size = 10000000

dct1 = defaultdict(list)
dct1 = {}
st_time = time()

for i in range(1, sample_size):
    s = str(i)
    key = s[0:1]
    name = 'server' + s
    dct1.setdefault(key, []).append({'name':name,'status':'RUNNING'})  # returns None!

print (f"\ndct1 defaultdict option: {time() - st_time}")

#print (dct1)  
# get one key
#one_key = dct1.get('2')
#print (one_key)
#for v in one_key:
#  print (v)

# print by key
#for k,v in dct1.items():
#  print("\nkey == {}".format(k))
#  print (v)
#  #for i in v:
#  #  print("  {} {}".format(i["name"], i["status"]))

dct2 = {}
st_time = time()

for i in range(1, sample_size):
    s = str(i)
    key = s[0:1]
    name = 'server' + s
    if key in dct2:
      dct2[key].append({'name':name,'status': 'STOPPED'})
    else:
      dct2.update({key: [{'name': name,'status': 'STOPPED'}]})

print (f"\ndct2 if .. in option: {time() - st_time}")

#print (dct2)
#one_key = dct1.get('1')
#print (one_key)
#for v in one_key:
#  print (v)

# print by key
#for k,v in dct2.items():
#  print("\nkey == {}".format(k))
#  print (v)
#  #for i in v:
#  #  print("  {} {}".format(i["name"], i["status"]))

test

py-assoc-arr$ python3 py-keyed-dict-timing.py 

dct1 defaultdict option: 6.392352342605591

dct2 if .. in option: 6.472132921218872