大约有 47,000 项符合查询结果（耗时：0.0478秒） [XML]
Sequence contains more than one element
...ault. This method will only succeed when the collections contains exactly 0 or 1 element. I believe you are looking for FirstOrDefault which will succeed no matter how many elements are in the collection.
share
|
...
Flatten nested dictionaries, compressing keys
...t(items)
>>> flatten({'a': 1, 'c': {'a': 2, 'b': {'x': 5, 'y' : 10}}, 'd': [1, 2, 3]})
{'a': 1, 'c_a': 2, 'c_b_x': 5, 'd': [1, 2, 3], 'c_b_y': 10}
share
|
improve this answer
|
...
Adding an arbitrary line to a matplotlib plot in ipython notebook
...as np
import matplotlib.pyplot as plt
np.random.seed(5)
x = np.arange(1, 101)
y = 20 + 3 * x + np.random.normal(0, 60, 100)
plt.plot(x, y, "o")
# draw vertical line from (70,100) to (70, 250)
plt.plot([70, 70], [100, 250], 'k-', lw=2)
# draw diagonal line from (70, 90) to (90, 200)
plt.plot([70,...
How are multi-dimensional arrays formatted in memory?
...things are going to happen. Here's a quick example:
int array1[3][2] = {{0, 1}, {2, 3}, {4, 5}};
In memory looks like this:
0 1 2 3 4 5
exactly the same as:
int array2[6] = { 0, 1, 2, 3, 4, 5 };
But if you try to pass array1 to this function:
void function1(int **a);
you'll get a warnin...
python plot normal distribution
...ot as plt
import numpy as np
import scipy.stats as stats
import math
mu = 0
variance = 1
sigma = math.sqrt(variance)
x = np.linspace(mu - 3*sigma, mu + 3*sigma, 100)
plt.plot(x, stats.norm.pdf(x, mu, sigma))
plt.show()
s...
surface plots in matplotlib
...t.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.show()
...
Turn a number into star rating display using jQuery and CSS
...tars, span.stars span {
display: block;
background: url(stars.png) 0 -16px repeat-x;
width: 80px;
height: 16px;
}
span.stars span {
background-position: 0 0;
}
Image
(source: ulmanen.fi)
Note: do NOT hotlink to the above image! Copy the file to your own server and u...
Can the Unix list command 'ls' output numerical chmod permissions?
...
it almost can ..
ls -l | awk '{k=0;for(i=0;i<=8;i++)k+=((substr($1,i+2,1)~/[rwx]/) \
*2^(8-i));if(k)printf("%0o ",k);print}'
share
|
improv...
Get loop count inside a Python FOR loop
...
605
The pythonic way is to use enumerate:
for idx,item in enumerate(list):
...
[] and {} vs list() and dict(), which is better?
...s/dicts:
>>> from timeit import timeit
>>> timeit("[]")
0.040084982867934334
>>> timeit("list()")
0.17704233359267718
>>> timeit("{}")
0.033620194745424214
>>> timeit("dict()")
0.1821558326547077
and for non-empty:
>>> timeit("[1,2,3]")
0.243...