Python dictionary: pop or del

Question

I haveing trouble understanding python dictonary

let say I have a dictornary called data that looks like this:

{ "computers": [
    {"Netbios_Name0": "apple1", "User_Domain0": "paradise", "User_Name0": "adam", "SMS_Installed_Sites0": "heaven", "Client_Version0": "5.00.9058.1018"}, 
    {"Netbios_Name0": "apple2", "User_Domain0": "paradise", "User_Name0": "lilith", "SMS_Installed_Sites0": "heaven", "Client_Version0": "5.00.9040.1044"}, 
    {"Netbios_Name0": "apple3", "User_Domain0": "paradise", "User_Name0": "eve", "SMS_Installed_Sites0": "heaven", "Client_Version0": "5.00.9068.1026"}
]}

and I want to remove apple2 so my end results looks like this:

{ "computers": [
    {"Netbios_Name0": "apple1", "User_Domain0": "paradise", "User_Name0": "adam", "SMS_Installed_Sites0": "heaven", "Client_Version0": "5.00.9058.1018"},  
    {"Netbios_Name0": "apple3", "User_Domain0": "paradise", "User_Name0": "eve", "SMS_Installed_Sites0": "heaven", "Client_Version0": "5.00.9068.1026"}
]}

I suspect I have to do something like this:

for item in data['computers']:
    if "apple2" in item['Netbios_Name0']:
        item.pop() # or del data[item]

But I can't get it to work.

item does not hang directly from data, but from data['computers'] so you should do `del data['computers'][item]` — , Apr 27 '22 at 11:40

Nin17 · Accepted Answer · 2022-04-27T11:52:24.483

You can use remove():

data = { "computers": [
    {"Netbios_Name0": "apple1", "User_Domain0": "paradise", "User_Name0": "adam", "SMS_Installed_Sites0": "heaven", "Client_Version0": "5.00.9058.1018"}, 
    {"Netbios_Name0": "apple2", "User_Domain0": "paradise", "User_Name0": "lilith", "SMS_Installed_Sites0": "heaven", "Client_Version0": "5.00.9040.1044"}, 
    {"Netbios_Name0": "apple3", "User_Domain0": "paradise", "User_Name0": "eve", "SMS_Installed_Sites0": "heaven", "Client_Version0": "5.00.9068.1026"}
]}

for item in list(data['computers']):
    if 'apple2' in item['Netbios_Name0']:
        data['computers'].remove(item)
data

Output:

{'computers': [{'Netbios_Name0': 'apple1',
   'User_Domain0': 'paradise',
   'User_Name0': 'adam',
   'SMS_Installed_Sites0': 'heaven',
   'Client_Version0': '5.00.9058.1018'},
  {'Netbios_Name0': 'apple3',
   'User_Domain0': 'paradise',
   'User_Name0': 'eve',
   'SMS_Installed_Sites0': 'heaven',
   'Client_Version0': '5.00.9068.1026'}]}

Patrick Artner · Answer 2 · 2022-04-27T11:51:19.523

You are iterating a list - you can pop from a list by index.

Never modify a lists length while while iterating: How to remove items from a list while iterating?

One way would be to store the indexes to be removed and remove them later:

data = { "computers": [
    {"Netbios_Name0": "apple1", "User_Domain0": "paradise", "User_Name0": "adam", 
     "SMS_Installed_Sites0": "heaven", "Client_Version0": "5.00.9058.1018"}, 
    {"Netbios_Name0": "apple2", "User_Domain0": "paradise", "User_Name0": "lilith", 
     "SMS_Installed_Sites0": "heaven", "Client_Version0": "5.00.9040.1044"}, 
    {"Netbios_Name0": "apple3", "User_Domain0": "paradise", "User_Name0": "eve", 
     "SMS_Installed_Sites0": "heaven", "Client_Version0": "5.00.9068.1026"}
]}

to_delete = []
for idx, inner_dic in enumerate(data['computers']):
    if "apple2" in inner_dic['Netbios_Name0']:
        to_delete.append(idx)
# remove biggest to lowest indexes - removing does not influence the order 
for idx in to_delete[::-1]:
    data['computers'].pop(idx)

print(data)

Output:

{'computers': 
    [{'Netbios_Name0': 'apple1', 'User_Domain0': 'paradise', 'User_Name0': 'adam', 
      'SMS_Installed_Sites0': 'heaven', 'Client_Version0': '5.00.9058.1018'}, 
     {'Netbios_Name0': 'apple3', 'User_Domain0': 'paradise', 'User_Name0': 'eve', 
      'SMS_Installed_Sites0': 'heaven', 'Client_Version0': '5.00.9068.1026'}]
}

score 0 · Answer 3 · answered Apr 27 '22 at 11:52

Python’s built-in enumerate function allows us to loop over a list and retrieve both the index and the value of each item in the list:

data = { "computers": [
    {"Netbios_Name0": "apple1", "User_Domain0": "paradise", "User_Name0": "adam", "SMS_Installed_Sites0": "heaven", "Client_Version0": "5.00.9058.1018"}, 
    {"Netbios_Name0": "apple2", "User_Domain0": "paradise", "User_Name0": "lilith", "SMS_Installed_Sites0": "heaven", "Client_Version0": "5.00.9040.1044"}, 
    {"Netbios_Name0": "apple3", "User_Domain0": "paradise", "User_Name0": "eve", "SMS_Installed_Sites0": "heaven", "Client_Version0": "5.00.9068.1026"}
]}

# Here 0 in 2nd argument is the starting number for num variable, can be used 0 to indicate as index
for num, computer in enumerate(data["computers"], 0):
    if computer["Netbios_Name0"] == "apple2":
        del data["computers"][num]

print(data)

This should work.

You can find more here: https://realpython.com/iterate-through-dictionary-python/

This doesn't work if ```'apple2'``` appears in more than one dictionary in the list. https://stackoverflow.com/questions/6260089/strange-result-when-removing-item-from-a-list-while-iterating-over-it — Nin17, Apr 27 '22 at 12:00
Never modify a list wile you iterate it. Use your code and a `data = { "computers": [{"Netbios_Name0": "apple1"}, {"Netbios_Name0": "apple2",}, {"Netbios_Name0": "apple2",}, {"Netbios_Name0": "apple2",}, {"Netbios_Name0": "apple3",}]}` and you'll get `{'computers': [{'Netbios_Name0': 'apple1'}, {'Netbios_Name0': 'apple2'}, {'Netbios_Name0': 'apple3'}]}` as result because modifying the list while iterating it breaks list ordering and iteration of it. — Patrick Artner, Apr 27 '22 at 12:47

Python dictionary: pop or del

3 Answers3