大约有 47,000 项符合查询结果（耗时：0.0477秒） [XML]
Pandas every nth row
...
207
I'd use iloc, which takes a row/column slice, both based on integer position and following norm...
Which is faster in Python: x**.5 or math.sqrt(x)?
...
math.sqrt(x) is significantly faster than x**0.5.
import math
N = 1000000
%%timeit
for i in range(N):
z=i**.5
10 loops, best of 3: 156 ms per loop
%%timeit
for i in range(N):
z=math.sqrt(i)
10 loops, best of 3: 91.1 ms per loop
Using Python 3.6....
Is there a NumPy function to return the first index of something in an array?
...mensions and it contained your item at two locations then
array[itemindex[0][0]][itemindex[1][0]]
would be equal to your item and so would
array[itemindex[0][1]][itemindex[1][1]]
numpy.where
share
|
...
Wolfram's Rule 34 in XKCD [closed]
The hover "joke" in #505 xkcd touts "I call rule 34 on Wolfram's Rule 34".
12 Answers
...
Java - get pixel array from image
...ation I was able to reduce the time of processing the pixels by more than 90% by just switching from the first approach to the second!
Here is a comparison I've setup to compare the two approaches:
import java.awt.image.BufferedImage;
import java.awt.image.DataBufferByte;
import java.io.IOExceptio...
Pandas get topmost n records within each group
...
>>> df.groupby('id').head(2)
id value
id
1 0 1 1
1 1 2
2 3 2 1
4 2 2
3 7 3 1
4 8 4 1
(Keep in mind that you might need to order/sort before, depending on your data)
EDIT: As mentioned by the questioner, use df.gro...
How to fix the uninitialized constant Rake::DSL problem on Heroku?
...
205
Put this in your Rakefile above require 'rake':
require 'rake/dsl_definition'
...
How to get a value from a cell of a dataframe?
...ue using the column name:
In [3]: sub_df
Out[3]:
A B
2 -0.133653 -0.030854
In [4]: sub_df.iloc[0]
Out[4]:
A -0.133653
B -0.030854
Name: 2, dtype: float64
In [5]: sub_df.iloc[0]['A']
Out[5]: -0.13365288513107493
...
Minimizing NExpectation for a custom distribution in Mathematica
...f we plot pdf2 it looks exactly as your Plot
Plot[pdf2[3.77, 1.34, -2.65, 0.40, x], {x, 0, .3}]
Now to the expected value. If I understand it correctly we have to integrate x * pdf[x] from -inf to +inf for a normal expected value.
x * pdf[x] looks like
Plot[pdf2[3.77, 1.34, -2.65, 0.40, x]*x...
Check if character is number?
...
70
You could use comparison operators to see if it is in the range of digit characters:
var c = ju...