从python字典中删除某些前缀的键的有效方法

Question

I have a python dictionary which looks something like this;

{'Prefix_1':'12', 'Prefix_2':'11', 'Prefix_3':'14', '1':'241', '2':'312', '3':'421'
}

I want to remove the key-value pairs of those with keys that start with 'Prefix'. The result should be a dictionary that look like this;

{'1':'241', '2':'312', '3':'421'
}

My current way of doing so is to remove each pair one by one by using del dictionary['Prefix_X'] . What are more efficient ways of doing so?

I am using python 2.7

Answer 1

Since the other answers all use dict comprehension to create a new dict and leave the original dict untouched, I'll give one that change the dict in place:

for k in d.keys():
    if k.startswith('Prefix'):
        d.pop(k)

Is there a better way?

Let's say there are N keys in the dictionary, to find all keys with the given prefix, you'll have to iterate over all the keys, and this is of O(N) time complexity.

Then you'll need to delete them one by one, in the worst case all of them are with the given prefix, so this is also of O(N) time complexity.

The total time complexity if O(N).

Answer 2

You could use a dict comprehension over the original dictionary:

D = {'Prefix_1':'12', 'Prefix_2':'11', 'Prefix_3':'14', '1':'241', '2':'312', '3':'421'

NewDict = {k: D[k] for k in D if not k.startswith('Prefix')}
NewDict
{'2': '312', '3': '421', '1': '241'}

Answer 3

use dictionary comprehensions

{k:v for k, v in d.items() if not k.startswith('Prefix')}

---

In [44]: {k:v for k, v in d.items() if not k.startswith('Prefix')}
Out[44]: {'1': '241', '2': '312', '3': '421'}

Answer 4

>>> z = {'Prefix_1':'12', 'Prefix_2':'11', 'Prefix_3':'14', '1':'241', '2':'312', '3':'421'}
>>> {k:v for k,v in z.items() if not k.startswith('Prefix')}
{'1': '241', '3': '421', '2': '312'}

Answer 5

d1 = {'Prefix_1':'12', 'Prefix_2':'11', 'Prefix_3':'14', '1':'241', '2':'312', '3':'421'}
d2 = {k: v for k, v in d1.iteritems() if not k.startswith('Prefix')}

print d1
print d2

Answer 6

Try to this.

for key in d.keys():
    if 'Prefix' in key:
        d.pop(key)