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Fastest way to replace NAs in a large data.table
... a large data.table , with many missing values scattered throughout its ~200k rows and 200 columns. I would like to re code those NA values to zeros as efficiently as possible.
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Which one will execute faster, if (flag==0) or if (0==flag)?
Interview question: Which one will execute faster, if (flag==0) or if (0==flag) ? Why?
16 Answers
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Remove outline from select box in FF
...he color of the dotted border. So say if you do...
select {
color: rgba(0,0,0,0);
}
Firefox will render the dotted border transparent. But of course your text will be transparent too! So we must somehow display the text. text-shadow comes to the rescue:
select {
color: rgba(0,0,0,0);
text-...
Replace all 0 values to NA
I have a dataframe with some numeric columns. Some row has a 0 value which should be considered as null in statistical analysis. What is the fastest way to replace all the 0 value to NULL in R?
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startsWith() and endsWith() functions in PHP
...eedle ) {
$length = strlen( $needle );
return substr( $haystack, 0, $length ) === $needle;
}
function endsWith( $haystack, $needle ) {
$length = strlen( $needle );
if( !$length ) {
return true;
}
return substr( $haystack, -$length ) === $needle;
}
Use this if you ...
Pandas index column title or name
...
In [8]: df.index.name = 'foo'
In [9]: df.index.name
Out[9]: 'foo'
In [10]: df
Out[10]:
Column 1
foo
Apples 1
Oranges 2
Puppies 3
Ducks 4
share
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What is the difference between ~> and >= when specifying rubygem in Gemfile?
... version provided and use that until it reaches a maximum version. So ~>0.8.5 is semantically equivalent to:
gem "cucumber", ">=0.8.5", "<0.9.0"
The easy way to think about it is that you're okay with the last digit incrementing to some arbitrary value, but the ones preceding it in the st...
Should I return EXIT_SUCCESS or 0 from main()?
...eing conflicting answers: should the main routine of a C++ program return 0 or EXIT_SUCCESS ?
8 Answers
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What ports does RabbitMQ use?
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edited Sep 19 '14 at 18:00
Eric Leschinski
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MySQL一次主从数据不一致的问题解决过程 - 数据库(内核) - 清泛网 - 专注C/...
...的数据补上
下面是能想到和找到的几个方案
1 从新从0开始同步，虽然对主库的使用没有影响，但是那么大的数据量，对性能，网络影响有点大，数据丢失的应该很少
2 主库dump数据，锁库，然后同步，不好。 影响业务使用 ...