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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 ...
...码试一下上面的第二点 （MD5是一种常用的Hash算法)
2.2.3 :003 > require 'digest/md5.so'
=> true
2.2.3 :004 > puts Digest::MD5.hexdigest('I love you')
e4f58a805a6e1fd0f6bef58c86f9ceb3
=> nil
2.2.3 :005 > puts Digest::MD5.hexdigest('I love you!')
690a8cda8894e37a6fff4d1790d53b...
Pass a data.frame column name to a function
... just use the column name directly:
df <- data.frame(A=1:10, B=2:11, C=3:12)
fun1 <- function(x, column){
max(x[,column])
}
fun1(df, "B")
fun1(df, c("B","A"))
There's no need to use substitute, eval, etc.
You can even pass the desired function as a parameter:
fun1 <- function(x, colu...
How do I install Python OpenCV through Conda?
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edited Jun 30 '17 at 10:00
Quanlong
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Why am I getting a “401 Unauthorized” error in Maven?
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JohnJohn
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How to select rows from a DataFrame based on column values?
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4135
To select rows whose column value equals a scalar, some_value, use ==:
df.loc[df['column_name'...
Cartesian product of x and y array points into single array of 2D points
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13 Answers
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What exactly does += do in python?
...r
return self.num
>>> a = Adder(2)
>>> a += 3
in __iadd__ 3
>>> a
5
Hope this helps.
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in_array multiple values
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answered Sep 24 '11 at 23:51
Mark ElliotMark Elliot
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What is the best regular expression to check if a string is a valid URL?
... wrote my URL (actually IRI, internationalized) pattern to comply with RFC 3987 (http://www.faqs.org/rfcs/rfc3987.html). These are in PCRE syntax.
For absolute IRIs (internationalized):
/^[a-z](?:[-a-z0-9\+\.])*:(?:\/\/(?:(?:%[0-9a-f][0-9a-f]|[-a-z0-9\._~\x{A0}-\x{D7FF}\x{F900}-\x{FDCF}\x{FDF0}-\x...
Efficient way to rotate a list in python
...method.
from collections import deque
items = deque([1, 2])
items.append(3) # deque == [1, 2, 3]
items.rotate(1) # The deque is now: [3, 1, 2]
items.rotate(-1) # Returns deque to original state: [1, 2, 3]
item = items.popleft() # deque == [2, 3]
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