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How can I remove all objects but one from the workspace in R?
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require(gdata)
keep(object_1,...,object_n,sure=TRUE)
ls()
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Eclipse/Java code completion not working
... triggers for Java:
abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ._
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In bash, how does one clear the current input?
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Found a short reference at http://www.ice2o.com/bash_quick_ref.html while searching.
ctrl + e (if not at the end of the line) plus ctrl + u will do it.
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Are memory leaks ever ok? [closed]
...responding free. An easy way to make one is like this:
#define BLK ((size_t)1024)
while(1){
void * vp = malloc(BLK);
}
Note that every time around the while(1) loop, 1024 (+overhead) bytes are allocated, and the new address assigned to vp; there's no remaining pointer to the previous malloc'...
Java naming convention for static final variables [duplicate]
...r abbreviations, all uppercase, with components
separated by underscore "_" characters. Constant names should be
descriptive and not unnecessarily abbreviated. Conventionally they may
be any appropriate part of speech. Examples of names for constants
include MIN_VALUE, MAX_VALUE, MIN_RADIX, ...
Change the font of a UIBarButtonItem
...Don't forget the exclamation mark (!) after the font. The error message: "'_' is not convertible to 'String'" is not really helpful.
– Ciryon
Sep 3 '15 at 6:41
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Mixing Angular and ASP.NET MVC/Web api?
...What happens with MVC routing? Do we use it at all? What happens now with "_Layout" view and @RenderBody()?
– AlexRebula
Jul 12 '15 at 12:02
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Creating email templates with Django
...e this:
from django.core.mail import EmailMultiAlternatives
subject, from_email, to = 'hello', 'from@example.com', 'to@example.com'
text_content = 'This is an important message.'
html_content = '<p>This is an <strong>important</strong> message.</p>'
msg = EmailMultiAlternat...
How expensive is RTTI?
...ime if you can afford to do
if (typeid(a) == typeid(b)) {
B* ba = static_cast<B*>(&a);
etc;
}
instead of
B* ba = dynamic_cast<B*>(&a);
if (ba) {
etc;
}
The former involves only one comparison of std::type_info; the latter necessarily involves traversing an inheritanc...
Determine the number of NA values in a column
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If you are looking for NA counts for each column in a dataframe then:
na_count <-sapply(x, function(y) sum(length(which(is.na(y)))))
should give you a list with the counts for each column.
na_count <- data.frame(na_count)
Should output the data nicely in a dataframe like:
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