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pandas: filter rows of DataFrame with operator chaining
... boolean index.
In [96]: df
Out[96]:
A B C D
a 1 4 9 1
b 4 5 0 2
c 5 5 1 0
d 1 3 9 6
In [99]: df[(df.A == 1) & (df.D == 6)]
Out[99]:
A B C D
d 1 3 9 6
If you want to chain methods, you can add your own mask method and use that one.
In [90]: def mask(df, key, ...
ATL正则表达式库使用 - C/C++ - 清泛网 - 专注C/C++及内核技术
...这样构造我们的CAtlRegExp类：
CAtlRegExp <> re;
re.Parse( "{[0-9]?[0-9]}:{[0-9][0-9]}" );
ATL的正则表达式语法和Perl的正则表达式语法大同小异，不过有一个值得注意的地方就 是ATL中用大括号（{ }）表示其匹配字符串中的Group，我们上...
Are Javascript arrays sparse?
...
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How exactly JavaScript arrays are implemented differs from browser to browser, but they generall...
How are the points in CSS specificity calculated
... algorithm is 256 or 28.
What this means is that a style specified with 0 ids and 256 class-names will over-ride a style specified with just 1 id. I tested this out with some fiddles:
255 classes are not enough to override 1 id
...but 256 classes are enough to override 1 id
...and 256 tag-name...
Find XOR of all numbers in a given range
...ven a large range [a,b] where 'a' and 'b' can be typically between 1 and 4,000,000,000 inclusive. You have to find out the XOR of all the numbers in the given range.
...
How can I check which version of Angular I'm using?
... itself.
Header of the current angular.js:
/**
* @license AngularJS v1.0.6
* (c) 2010-2012 Google, Inc. http://angularjs.org
* License: MIT
*/
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Using numpy to build an array of all combinations of two arrays
...
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Which is faster in Python: x**.5 or math.sqrt(x)?
...
math.sqrt(x) is significantly faster than x**0.5.
import math
N = 1000000
%%timeit
for i in range(N):
z=i**.5
10 loops, best of 3: 156 ms per loop
%%timeit
for i in range(N):
z=math.sqrt(i)
10 loops, best of 3: 91.1 ms per loop
Using Python 3.6....
Disable/turn off inherited CSS3 transitions
..." class="transition">Content</a>
...and CSS:
a {
color: #f90;
-webkit-transition:color 0.8s ease-in, background-color 0.1s ease-in ;
-moz-transition:color 0.8s ease-in, background-color 0.1s ease-in;
-o-transition:color 0.8s ease-in, background-color 0.1s ease-in;
...
Mapping two integers to one, in a unique and deterministic way
...sy to define a bijection f : Z -> N, like so:
f(n) = n * 2 if n >= 0
f(n) = -n * 2 - 1 if n < 0
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