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How to count TRUE values in a logical vector
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There are some problems when logical vector contains NA values.
See for example:
z <- c(TRUE, FALSE, NA)
sum(z) # gives you NA
table(z)["TRUE"] # gives you 1
length(z[z == TRUE]) # f3lix answer, gives you 2 (because NA indexing retur...
How to create a directory and give permission in single command
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According to mkdir's man page...
mkdir -m 777 dirname
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How to get a random number in Ruby
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Finally, if you just need a random float, just call rand with no arguments.
As Marc-André Lafortune mentions in his answer below (go upvote it), Ruby 1.9.2 has its own Random class (that Marc-André himself helped to debug, hence the 1.9.2 target for that feature).
For instance, in this ...
Is it possible to ping a server from Javascript?
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I have found someone that accomplishes this with a very clever usage of the native Image object.
From their source, this is the main function (it has dependences on other parts of the source but you get the idea).
function Pinger_ping(ip...
store and retrieve a class object in shared preference
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Thanks.I want to store some data members of the class.And i don't want to store each values of data members using shared preference.I want to store it as an object.If not shared preference what are my other options?
– androidGuy...
How does one reorder columns in a data frame?
How would one change this input (with the sequence: time, in, out, files):
11 Answers
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How to simulate a mouse click using JavaScript?
I know about the document.form.button.click() method. However, I'd like to know how to simulate the onclick event.
7 An...
Is it a bad practice to use negative margins in Android?
... Seems to be a harmless thing then, leaving open in case anyone has some other insight
– Juan Cortés
May 20 '12 at 13:17
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How to implement a rule engine?
...ode (using Expression trees) and does not need any complicated switch statements:
(Edit : full working example with generic method)
public Func<User, bool> CompileRule(Rule r)
{
var paramUser = Expression.Parameter(typeof(User));
Expression expr = BuildExpr(r, paramUser);
// build ...
What is the difference between the different methods of putting JavaScript code in an ?
I have seen the following methods of putting JavaScript code in an <a> tag:
7 Answers
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