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Why does the order of the loops affect performance when iterating over a 2D array?
...y location in the array: x[i][j]. Here's a bit of insight why:
You have a 2-dimensional array, but memory in the computer is inherently 1-dimensional. So while you imagine your array like this:
0,0 | 0,1 | 0,2 | 0,3
----+-----+-----+----
1,0 | 1,1 | 1,2 | 1,3
----+-----+-----+----
2,0 | 2,1 | 2,2 ...
Find the max of two or more columns with pandas
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VIP会员中心 · App Inventor 2 中文网，少儿编程陪伴者
... AI伴侣：v2.69 MIT官方：v2.69 发布日志 首页 VIP会员中心 中文社...
How to deal with SettingWithCopyWarning in Pandas?
...copy. [see GH5390 and GH5597 for background discussion.]
df[df['A'] > 2]['B'] = new_val # new_val not set in df
The warning offers a suggestion to rewrite as follows:
df.loc[df['A'] > 2, 'B'] = new_val
However, this doesn't fit your usage, which is equivalent to:
df = df[df['A'] > ...
How can I debug git/git-shell related problems?
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217
For even more verbose output use following:
GIT_CURL_VERBOSE=1 GIT_TRACE=1 git pull origin ma...
Can dplyr package be used for conditional mutating?
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220
Use ifelse
df %>%
mutate(g = ifelse(a == 2 | a == 5 | a == 7 | (a == 1 & b == 4), 2,
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程序员之网络安全系列（二）：如何安全保存用户密码及哈希算法 - 更多技术 ...
...唯一且极其紧凑的数值表示形式. 典型的哈希算法包括 MD2、MD4、MD5 和 SHA-1
Hash算法是给消息生成摘要，那么什么是摘要呢？
举个例子： > 比如你给你女朋友写了一封邮件，确保没被人改过，你可以生成这样一份摘要 “第50个字...
Python creating a dictionary of lists
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286
You can use defaultdict:
>>> from collections import defaultdict
>>> d = de...
Ruby 2.0.0p0 IRB warning: “DL is deprecated, please use Fiddle”
...ions of Ruby, removed all of my gems
(including Rails), and installed Ruby 2.0. In other words, a totally clean re-install. Upon starting IRB, I received this message:
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