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Swapping column values in MySQL
I have a MySQL table with coordinates, the column names are X and Y. Now I want to swap the column values in this table, so that X becomes Y and Y becomes X. The most apparent solution would be renaming the columns, but I don't want to make structure changes since I don't necessarily have permission...
Regex expressions in Java, \\s vs. \\s+
What's the difference between the following two expressions?
4 Answers
4
...
Why does @foo.setter in Python not work for me?
...r class as MyClass(object):
class testDec(object):
@property
def x(self):
print 'called getter'
return self._x
@x.setter
def x(self, value):
print 'called setter'
self._x = value
It works:
>>> k = testDec()
>>> k.x
called gett...
Adding a legend to PyPlot in Matplotlib in the simplest manner possible
...d with Python 3.8.0):
import numpy as np
import matplotlib.pyplot as plt
x = np.linspace(0, 20, 1000)
y1 = np.sin(x)
y2 = np.cos(x)
plt.plot(x, y1, "-b", label="sine")
plt.plot(x, y2, "-r", label="cosine")
plt.legend(loc="upper left")
plt.ylim(-1.5, 2.0)
plt.show()
Slightly modified from this ...
Calculating Pearson correlation and significance in Python
...;>>
Help on function pearsonr in module scipy.stats.stats:
pearsonr(x, y)
Calculates a Pearson correlation coefficient and the p-value for testing
non-correlation.
The Pearson correlation coefficient measures the linear relationship
between two datasets. Strictly speaking, Pearson's corr...
Can Python test the membership of multiple values in a list?
...est if two or more values have membership on a list, but I'm getting an unexpected result:
10 Answers
...
what is the difference between 'transform' and 'fit_transform' in sklearn
In the sklearn-python toolbox, there are two functions transform and fit_transform about sklearn.decomposition.RandomizedPCA . The description of two functions are as follows
...
Swapping two variable value without using third variable
...
Using the xor swap algorithm
void xorSwap (int* x, int* y) {
if (x != y) { //ensure that memory locations are different
*x ^= *y;
*y ^= *x;
*x ^= *y;
}
}
Why the test?
The test is to ensure that x an...
delete a.x vs a.x = undefined
...
They are not equivalent. The main difference is that setting
a.x = undefined
means that a.hasOwnProperty("x") will still return true, and therefore, it will still show up in a for in loop, and in Object.keys()
delete a.x
means that a.hasOwnProperty("x") will return false
The way th...