August 2015
Intermediate to advanced
384 pages
7h 42m
Chinese
Content preview from 高效能PYTHON程式設計
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.
116
|
第六章
進入 numpy
為了處理使用
perf
發現的記憶體破碎，我們必須找到能夠有效地將操作向量化的套件，
幸運的是，
numpy
擁有我們需要的一切功能—它將資料儲存在連續的記憶體區塊中，並
且支援資料的向量化操作，因此，我們對
numpy
陣列所做的計算全都以區塊的形式發
生，而不需要特地去繞行每個元素，這樣不僅讓矩陣計算容易很多，並且更加快速。讓
我們看一個範例︰
from array import array
import numpy
def norm_square_list(vector):
"""
>>> vector = range(1000000)
>>> %timeit norm_square_list(vector_list)
1000 loops, best of 3: 1.16 ms per loop
"""
norm = 0
for v in vector:
norm += v*v
return norm
def norm_square_list_comprehension(vector):
"""
>>> vector = range(1000000)
>>> %timeit norm_square_list_comprehension(vector_list)
1000 loops, best of 3: 913 μs per loop
"""
return sum([v*v for v in vector])
def norm_squared_generator_comprehension(vector): ...
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Read now
Unlock full access
More than 5,000 organizations count on O’Reilly
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.