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surface plots in matplotlib
...
fig = plt.figure()
ax = fig.add_subplot(111, projection='3d')
x = y = np.arange(-3.0, 3.0, 0.05)
X, Y = np.meshgrid(x, y)
zs = np.array(fun(np.ravel(X), np.ravel(Y)))
Z = zs.reshape(X.shape)
ax.plot_surface(X, Y, Z)
ax.set_xlabel('X Label')
ax.set_ylabel('Y Label')
ax.set_zlabel('Z Label')
plt.s...
How to generate a random number in C++?
... with implementation-defined algorithm. Function rand() produces values in range [0, RAND_MAX].
Quote from C11 standard (ISO/IEC 9899:2011):
The srand function uses the argument as a seed for a new sequence of
pseudo-random numbers to be returned by subsequent calls to rand. If
srand is then called...
Too many 'if' statements?
... exception of the i/j/k convention for loop variables), named constants, arranging my code in a readable fashion, etc., but when the variable and function names start taking up more than 20 characters each I find it actually leads to less readable code. My usual approach is to try for comprehensible...
The most efficient way to implement an integer based power function pow(int, int)
... // Does not work for negative exponents. (But that would be leaving the range of int)
if (exponent == 0) return 1; // base case;
int temp = pow(base, exponent/2);
if (exponent % 2 == 0)
return temp * temp;
else
return (base * temp * temp);
}
...
How to remove multiple indexes from a list at the same time? [duplicate]
...indices]
Example:
In [9]: remove_indices = [1,2,3]
In [10]: somelist = range(10)
In [11]: somelist = [i for j, i in enumerate(somelist) if j not in remove_indices]
In [12]: somelist
Out[12]: [0, 4, 5, 6, 7, 8, 9]
shar...
MySQL vs MongoDB 1000 reads
...index, we can assume that the values for the root row are in the index
20+ range lookups (hopefully on an index) for the entity's pk value
These probably aren't clustered indexes, so the same 20+ data lookups once we figure out what the appropriate child rows are.
So the total for mysql, even assu...
Is the “struct hack” technically undefined behavior?
...des in the list of undefined behavior:
An array subscript is out of range, even if an object is apparently accessible with the given subscript (as in the lvalue expression a[1][7] given the declaration int a[4][5]) (6.5.6).
Paragraph 8 of Section 6.5.6 Additive operators has another ment...
Differences between INDEX, PRIMARY, UNIQUE, FULLTEXT in MySQL?
... your data so they are used only for access - for quickly reaching certain ranges of records without scanning all records.
UNIQUE refers to an index where all rows of the index must be unique. That is, the same row may not have identical non-NULL values for all columns in this index as another row...
How to print a string in fixed width?
... your combinations in one line with:
>>> [''.join(perm) for i in range(1, len(s)) for perm in it.permutations(s, i)]
['a', 'b', 'c', 'd', 'ab', 'ac', 'ad', 'ba', 'bc', 'bd', 'ca', 'cb', 'cd', 'da', 'db', 'dc', 'abc', 'abd', 'acb', 'acd', 'adb', 'adc', 'bac', 'bad', 'bca', 'bcd', 'bda', 'bd...
Cannot instantiate the type List [duplicate]
...
Raw collection types are dangerous and should not be used or suggested for use in any new code targeted for Java 5+, end of story.
– Matt Ball
Oct 31 '11 at 22:15
...