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Position of least significant bit that is set
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170
Bit Twiddling Hacks offers an excellent collection of, er, bit twiddling hacks, with performan...
Java - get pixel array from image
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182
I was just playing around with this same subject, which is the fastest way to access the pixel...
Find the max of two or more columns with pandas
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185
You can get the maximum like this:
>>> import pandas as pd
>>> df = pd.Data...
How do I get indices of N maximum values in a NumPy array?
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16 Answers
16
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Convert an image to grayscale in HTML/CSS
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731
Support for CSS filters has landed in Webkit. So we now have a cross-browser solution.
img...
How many double numbers are there between 0.0 and 1.0?
...or example, that's the number of distinct doubles between 0.5 included and 1.0 excluded, and exactly that many also lie between 1.0 included and 2.0 excluded, and so forth.
Counting the doubles between 0.0 and 1.0 is harder than doing so between powers of two, because there are many powers of two i...
pyplot scatter plot marker size
...d the output they produce.
# doubling the width of markers
x = [0,2,4,6,8,10]
y = [0]*len(x)
s = [20*4**n for n in range(len(x))]
plt.scatter(x,y,s=s)
plt.show()
gives
Notice how the size increases very quickly. If instead we have
# doubling the area of markers
x = [0,2,4,6,8,10]
y = [0]*len(...
From ND to 1D arrays
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Use np.ravel (for a 1D view) or np.ndarray.flatten (for a 1D copy) or np.ndarray.flat (for an 1D iterator):
In [12]: a = np.array([[1,2,3], [4,5,6]])
In [13]: b = a.ravel()
In [14]: b
Out[14]: array([1, 2, 3, 4, 5, 6])
Note that ravel() ret...
CSS triangle custom border color
...atibility. I am trying to have the triangle have a white background with a 1px border (around the angled sides of the triangle) with color #CAD5E0. Is this possible? Here's what I have so far:
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