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xkcd style graphs in MATLAB
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I see two ways to solve this: The first way is to add some jitter to the x/y coordinates of the plot features. This has the advantage that you can easily modify a plot, but you have to draw the axes yourself if you want to have them xkcdyfied (see @Rody Oldenhuis' solution). The second way is to c...
How to use filter, map, and reduce in Python 3
filter , map , and reduce work perfectly in Python 2. Here is an example:
7 Answers
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Sort a list by multiple attributes?
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A key can be a function that returns a tuple:
s = sorted(s, key = lambda x: (x[1], x[2]))
Or you can achieve the same using itemgetter (which is faster and avoids a Python function call):
import operator
s = sorted(s, key = operator.itemgetter(1, 2))
And notice that here you can use sort inst...
How do I replace NA values with zeros in an R dataframe?
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See my comment in @gsk3 answer. A simple example:
> m <- matrix(sample(c(NA, 1:10), 100, replace = TRUE), 10)
> d <- as.data.frame(m)
V1 V2 V3 V4 V5 V6 V7 V8 V9 V10
1 4 3 NA 3 7 6 6 10 6 5
2 9 8 9 5 10 NA 2 1 7 2
3 1 1 6 3 6 ...
Equation for testing if a point is inside a circle
If you have a circle with center (center_x, center_y) and radius radius , how do you test if a given point with coordinates (x, y) is inside the circle?
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How can we make xkcd style graphs?
Apparently, folk have figured out how to make xkcd style graphs in Mathematica and in LaTeX . Can we do it in R? Ggplot2-ers? A geom_xkcd and/or theme_xkcd?
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How do function pointers in C work?
I had some experience lately with function pointers in C.
11 Answers
11
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Simultaneously merge multiple data.frames in a list
...icate of this one so I answer here, using the 3 sample data frames below:
x <- data.frame(i = c("a","b","c"), j = 1:3, stringsAsFactors=FALSE)
y <- data.frame(i = c("b","c","d"), k = 4:6, stringsAsFactors=FALSE)
z <- data.frame(i = c("c","d","a"), l = 7:9, stringsAsFactors=FALSE)
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Callback functions in C++
...s of the standard algorithms library <algorithm> use callbacks. For example the for_each algorithm applies an unary callback to every item in a range of iterators:
template<class InputIt, class UnaryFunction>
UnaryFunction for_each(InputIt first, InputIt last, UnaryFunction f)
{
for (...
How to find the statistical mode?
In R, mean() and median() are standard functions which do what you'd expect. mode() tells you the internal storage mode of the object, not the value that occurs the most in its argument. But is there is a standard library function that implements the statistical mode for a vector (or list)?
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