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CPU Privilege Rings: Why rings 1 and 2 aren't used?
...of the modern protection model) only has a concept of privileged (ring 0,1,2) and unprivileged, the benefit to rings 1 and 2 were diminished greatly.
The intent by Intel in having rings 1 and 2 is for the OS to put device drivers at that level, so they are privileged, but somewhat separated from th...
Single Line Nested For Loops
...
172
The best source of information is the official Python tutorial on list comprehensions. List com...
How do I check the difference, in seconds, between two dates?
...ates, use total_seconds like this:
import datetime as dt
a = dt.datetime(2013,12,30,23,59,59)
b = dt.datetime(2013,12,31,23,59,59)
(b-a).total_seconds()
86400.0
#note that seconds doesn't give you what you want:
(b-a).seconds
0
...
How to count the number of true elements in a NumPy bool array
...
265
You have multiple options. Two options are the following.
numpy.sum(boolarr)
numpy.count_nonz...
Clojure: cons (seq) vs. conj (list)
...guments to insert into a collection, while cons takes just one:
(conj '(1 2 3) 4 5 6)
; => (6 5 4 1 2 3)
(cons 4 5 6 '(1 2 3))
; => IllegalArgumentException due to wrong arity
Another difference is in the class of the return value:
(class (conj '(1 2 3) 4))
; => clojure.lang.Persistent...
How do I find if a string starts with another string in Ruby?
...
263
puts 'abcdefg'.start_with?('abc') #=> true
[edit] This is something I didn't know before...
One-line list comprehension: if-else variants
...
342
x if y else z is the syntax for the expression you're returning for each element. Thus you need:...
What's the difference between lists enclosed by square brackets and parentheses in Python?
...
278
Square brackets are lists while parentheses are tuples.
A list is mutable, meaning you can ch...
How to determine whether a Pandas Column contains a particular value
...ther the value is in the index:
In [11]: s = pd.Series(list('abc'))
In [12]: s
Out[12]:
0 a
1 b
2 c
dtype: object
In [13]: 1 in s
Out[13]: True
In [14]: 'a' in s
Out[14]: False
One option is to see if it's in unique values:
In [21]: s.unique()
Out[21]: array(['a', 'b', 'c'], dtype=o...
What does the tilde (~) mean in my composer.json file?
...de means next significant release. In your case, it is equivalent to >= 2.0, < 3.0.
The full explanation is at Tilde Version Range docs page:
The ~ operator is best explained by example: ~1.2 is equivalent to >=1.2 <2.0.0, while ~1.2.3 is equivalent to >=1.2.3 <1.3.0.
Ano...