I am trying to remove a dictionary from a list if it already exists but it doesn't seem to be working. Can anyone see what I am doing wrong or advise me what I should be doing
new_dict = {'value': 'some value', 'key': 'someKey'}
if new_dict in my_list:
my_list.remove(new_dict)
new_list is a list of dictionaries where new_dict is definitely in
如果new_dict
在my_list
是“绝对”的话,那么my_list.remove(new_dict)
应该这样做(即, if new_dict in my_list
不需要if new_dict in my_list
,只会减慢它的速度)。
my_list = [1,{'value':'some value', 'key' :'somekey'}, 2, {'z':'z', 'x': 'x'}]
new_dict = {'value':'some value', 'key' :'somekey'}
#new_dict = {'z':'z', 'x': 'x'}
differ = 0
matched = 0
for element in my_list:
if type(element) is types.DictType and matched != 0:
differ = 0
# check if dictionary keys match
if element.viewkeys() == new_dict.viewkeys():
# check if dictionary values match
for key in element.keys():
if element[key] != new_dict[key]:
differ = 1
matched = 1
if differ != 1:
my_list.remove(new_dict)
print my_list
It worked for both of the dictionaries for me.
In most cases it is clever to build a new list:
new_list = [ dd for dd in my_list if not dd is new_dict ]
This is typical for a functional programming style, as it avoids side effects. Imagine if you use your solution in a function or method. In most cases you need a modified list only for internal purposes, then modifying an input parameter is dangerous.
Your problem may come from the fact that removing from a list while iterating over the same list is not safe. What you want to do is something like:
copied_list = my_list[:]
if new_dict in copied_list:
my_list.remove(new_dict)
This way, you iterate over a copy of the list and remove from the original.
This may not be the cause of your problem though. It would be interesting to see:
my_list
my_list
after the loop, ie how do you realise your dictionary was not removed
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