大约有 40,000 项符合查询结果（耗时：0.0642秒） [XML]
Subset of rows containing NA (missing) values in a chosen column of a data frame
...ated. THe point is to use is.na, I wrongly interpreted you wanted to check all variables.
– Joris Meys
Nov 2 '11 at 21:34
3
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How do you push a Git tag to a branch using a refspec?
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How does this actually solve the original poster's problem about overwriting a branch with a tag by force-pushing it? This just pushes all of your tags to a remote, it won't overwrite any branches.
– user456814
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How can I get the sha1 hash of a string in node.js?
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Good idea. Note, however, that all objects (except arrays and null) will have the same sha1sum value since Object.toString() returns [object Object] by default. So sha1sum({}) === sha1sum({"foo":"bar"}) === sha1sum({"a":1}), etc.
– m...
Markdown and including multiple files
Is there any markdown fork that allows you to reference other files, something like an includes file? Specifically, I want to create a separate markdown file with links that I call often but not always (call this B.md), then when I link by reference in the md file I'm writing (A.md), I'd like it to ...
clang: how to list supported target architectures?
Currently I am interested in ARM in general and specifically iphone/android targets. But I just want to know more about clang, since it feels to play important role in the years to come.
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Static class initializer in PHP
I have an helper class with some static functions. All the functions in the class require a ‘heavy’ initialization function to run once (as if it were a constructor).
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Nested or Inner Class in PHP
...There are several compelling reasons for using them:
It is a way of logically grouping classes that are only used in one place.
If a class is useful to only one other class, then it is logical to
relate and embed it in that class and keep the two together.
It increases encapsulation.
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Is the order of elements in a JSON list preserved?
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Practically speaking, if the keys were of type NaN, the browser will not change the order.
The following script will output "One", "Two", "Three":
var foo={"3":"Three", "1":"One", "2":"Two"};
for(bar in foo) {
alert(foo[bar]);...
What is your favorite C programming trick? [closed]
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C99 offers some really cool stuff using anonymous arrays:
Removing pointless variables
{
int yes=1;
setsockopt(yourSocket, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(int));
}
becomes
setsockopt(yourSocket, SOL_SOCKET, SO_REUSEADDR...
What makes a SQL statement sargable?
...L optimizer can't use an index on myDate, even if one exists. It will literally have to evaluate this function for every row of the table. Much better to use:
WHERE myDate >= '01-01-2008' AND myDate < '01-01-2009'
Some other examples:
Bad: Select ... WHERE isNull(FullName,'Ed Jones') = 'Ed...