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Convert RGB to RGBA over white
I have a hex color, e.g. #F4F8FB (or rgb(244, 248, 251) ) that I want converted into an as-transparent-as-possible rgba color (when displayed over white). Make sense? I'm looking for an algorithm, or at least idea of an algorithm for how to do so.
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Why is `[` better than `subset`?
When I need to filter a data.frame, i.e., extract rows that meet certain conditions, I prefer to use the subset function:
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Sorting Python list based on the length of the string
...n an integer, not a boolean. So your code should instead read as follows:
xs.sort(lambda x,y: cmp(len(x), len(y)))
Note that cmp is a builtin function such that cmp(x, y) returns -1 if x is less than y, 0 if x is equal to y, and 1 if x is greater than y.
Of course, you can instead use the key para...
Extracting bits with a single multiplication
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Very interesting question, and clever trick.
Let's look at a simple example of getting a single byte manipulated. Using unsigned 8 bit for simplicity. Imagine your number is xxaxxbxx and you want ab000000.
The solution consisted of two steps: a bit masking, followed by multiplication. The bit...
How can I convert String to Int?
I have a TextBoxD1.Text and I want to convert it to an int to store it in a database.
30 Answers
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How to get number of entries in a Lua table?
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I still shudder at the memory of my experience with Lua, when I first realised that the return value of a basic operator like # is not deterministic.
– Roman Starkov
May 5 '12 at 17:07
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Real mouse position in canvas [duplicate]
..., evt) {
var rect = canvas.getBoundingClientRect();
return {
x: evt.clientX - rect.left,
y: evt.clientY - rect.top
};
}
Just call it from your event with the event and canvas as arguments. It returns an object with x and y for the mouse positions.
As the mouse position you...
How to use a variable to specify column name in ggplot
...<- function( column ) {
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ggplot( rates.by.groups, aes_string(x="name", y="rate", colour= column,
group=column ) )
}
as long as you pass the column to the function as a string (f("majr") rather than f(majr)). Also note that we changed the other ...
Why is the apt-get function not working in the terminal on Mac OS X v10.9 (Mavericks)?
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Mac OS X doesn't have apt-get. There is a package manager called Homebrew that is used instead.
This command would be:
brew install python
Use Homebrew to install packages that you would otherwise use apt-get for.
The page I linke...