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搭建高可用mongodb集群（三）—— 深入副本集内部机制 - 大数据 & AI - 清...
...命令可以登录主节点使用
db.adminCommand({replSetStepDown : 1})
如果杀不掉可以使用强制开关
db.adminCommand({replSetStepDown : 1, force : true})
或者使用 rs.stepDown(120)也可以达到同样的效果，中间的数字指不能在停止服务这段时间成...
bash/fish command to print absolute path to a file
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591
Use realpath
$ realpath example.txt
/home/username/example.txt
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How to perform element-wise multiplication of two lists?
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14 Answers
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jQuery map vs. each
...ion you can potentially waste a lot of memory.
For example:
var items = [1,2,3,4];
$.each(items, function() {
alert('this is ' + this);
});
var newItems = $.map(items, function(i) {
return i + 1;
});
// newItems is [2,3,4,5]
You can also use the map function to remove an item from an array...
Relative frequencies / proportions with dplyr
...se(n = n()) %>%
mutate(freq = n / sum(n))
# am gear n freq
# 1 0 3 15 0.7894737
# 2 0 4 4 0.2105263
# 3 1 4 8 0.6153846
# 4 1 5 5 0.3846154
From the dplyr vignette:
When you group by multiple variables, each summary peels off one level of the grouping. That mak...
How to use Active Support core extensions
I have Active Support 3.0.3 installed and Rails 3.0.3 with Ruby 1.8.7.
5 Answers
5
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How do you match only valid roman numerals with a regular expression?
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16 Answers
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CSS3 Transparency + Gradient
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edited Jun 16 '12 at 16:08
umassthrower
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Passing parameters to JavaScript files
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14 Answers
14
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Best way to merge two maps and sum the values of same key?
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15 Answers
15
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