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Principal component analysis in Python
...nalysis
Usage:
p = PCA( A, fraction=0.90 )
In:
A: an array of e.g. 1000 observations x 20 variables, 1000 rows x 20 columns
fraction: use principal components that account for e.g.
90 % of the total variance
Out:
p.U, p.d, p.Vt: from numpy.linalg.svd, A = U . d . Vt
p.di...
Understanding generators in Python
... x = x + 1
if x % 3 == 0:
yield x
for a in mygen(100):
print a
There is a loop in the generator that runs from 0 to n, and if the loop variable is a multiple of 3, it yields the variable.
During each iteration of the for loop the generator is executed. If it is the f...
How do I install Python OpenCV through Conda?
...deo can be opened, I wanted to confirm that I could extract a frame (frame 100) as an array. In openCV 2.4.9, the command for this was cap.set(cv2.cv.CV_CAP_PROP_POS_FRAMES, 100). In openCV 3.2.0, the equivalent command has changed to cap.set(cv2.CAP_PROP_POS_FRAMES, 100)
– oll...
MLKitLanguageId 拓展：离线语言识别 · App Inventor 2 中文网
...LanguageId 拓展
判断一段文本是哪种语言，支持 100 多种。
为什么选它：
完全离线。模型随 .aix 打包，设备不需要 Google Play 服务，断网也能用。
只有 4.0 MB —— 这是我们整个 ML Kit 拓展家族里最小的一个。
不用...
C++ lambda with captures as a function pointer
...SBKerrek SB
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3
...
How do I toggle an element's class in pure JavaScript?
... classes + class1;
}
.red {
background-color: red
}
div {
width: 100px;
height: 100px;
margin-bottom: 10px;
border: 1px solid black;
}
<div class="does red redAnother " onclick="toogleClass(this, 'red')"></div>
<div class="does collapse navbar-collapse " onclic...
What is the difference between `sorted(list)` vs `list.sort()`?
...'s our setup:
import timeit
setup = """
import random
lists = [list(range(10000)) for _ in range(1000)] # list of lists
for l in lists:
random.shuffle(l) # shuffle each list
shuffled_iter = iter(lists) # wrap as iterator so next() yields one at a time
"""
And here's our results for a list of...
MFC OnEraseBkgnd浅析 - C/C++ - 清泛网 - 专注C/C++及内核技术
.../需要修改的控件标题
pWnd ->GetParent()->InvalidateRect(CRect(0,0,100,50),TRUE);
pWnd ->GetParent()->InvalidateRect(CRect(0,0,100,50),TRUE);
this->RedrawWindow();
MFC OnEraseBkgnd
Java int to String - Integer.toString(i) vs new Integer(i).toString()
...ce then the Integer.toString(i); is expensive if you are calling less than 100 million times. Else if it is more than 100 million calls then the new Integer(10).toString() will perform better.
Below is the code through u can try to measure the performance,
public static void main(String args[]) {
...
Why not use Double or Float to represent currency?
...y do
you have left?
System.out.println(1.03 - .42);
prints out 0.6100000000000001.
The right way to solve this problem is
to use BigDecimal, int or long
for monetary calculations.
Though BigDecimal has some caveats (please see currently accepted answer).
...