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Summarizing multiple columns with dplyr? [duplicate]
...brary(dplyr)
library(purrrlyr)
library(data.table)
library(bench)
set.seed(123)
n <- 10000
df <- data.frame(
a = sample(1:5, n, replace = TRUE),
b = sample(1:5, n, replace = TRUE),
c = sample(1:5, n, replace = TRUE),
d = sample(1:5, n, replace = TRUE),
grp = sample(1:3, n, replac...
Python how to write to a binary file?
...FileBytes)
bytearray(b'{\x03\xff\x00d')
>>> bytes(newFileBytes)
'[123, 3, 255, 0, 100]'
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Does Python have “private” variables in classes?
...names the variable.
class A:
def __init__(self):
self.__var = 123
def printVar(self):
print self.__var
Now, if you try to access __var outside the class definition, it will fail:
>>>x = A()
>>>x.__var # this will return error: "A has no attribute __var...
Retrieving parameters from a URL
...
import urlparse
url = 'http://example.com/?q=abc&p=123'
par = urlparse.parse_qs(urlparse.urlparse(url).query)
print par['q'][0], par['p'][0]
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jQuery deferreds and promises - .then() vs .done()
...tion (x) { // Suppose promise returns "abc"
console.log(x);
return 123;
}).then(function (x){
console.log(x);
}).then(function (x){
console.log(x)
})
The following results will get logged:
abc
123
undefined
While
promise.done(function (x) { // Suppose promise returns "abc"
...
Disabled href tag
...
You can use:
<a href="/" onclick="return false;">123n</a>
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Write a number with two decimal places SQL server
...ters to display, and the number of decimal places to display
Select Str(12345.6789, 12, 3)
displays: ' 12345.679' ( 3 spaces, 5 digits 12345, a decimal point, and three decimal digits (679). - it rounds if it has to truncate, (unless the integer part is too large for the total size, in whic...
Map vs Object in JavaScript
...d Symbol keys where as Maps support more or less any key type.
If I do obj[123] = true and then Object.keys(obj) then I will get ["123"] rather than [123]. A Map would preserve the type of the key and return [123] which is great. Maps also allow you to use Objects as keys. Traditionally to do this y...
Why does Javascript's regex.exec() not always return the same value? [duplicate]
...ignment as the loop condition.
var re = /foo_(\d+)/g,
str = "text foo_123 more text foo_456 foo_789 end text",
match,
results = [];
while (match = re.exec(str))
results.push(+match[1]);
DEMO: http://jsfiddle.net/pPW8Y/
If you don't like the placement of the assignment, the loo...
linux svn搭建配置及svn命令详解 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...asswd
[users]
# harry = harryssecret
# sally = sallyssecret
hello=123
用户名=密码
这样我们就建立了hello用户， 123密码
2.2 再设置权限authz
[root@www ~]# vi authz
[/]
hello= rw
意思是hello用户对所有的目录有读写权限，当然也...