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What is the 'pythonic' equivalent to the 'fold' function from functional programming?
...ce (from the functools module) and the operator module, e.g.:
def product(xs):
return reduce(operator.mul, xs, 1)
Be aware that reduce is actually a foldl, in Haskell terms. There is no special syntax to perform folds, there's no builtin foldr, and actually using reduce with non-associative o...
Find indices of elements equal to zero in a NumPy array
...
numpy.where() is my favorite.
>>> x = numpy.array([1,0,2,0,3,0,4,5,6,7,8])
>>> numpy.where(x == 0)[0]
array([1, 3, 5])
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How to “properly” print a list?
...
In Python 2:
mylist = ['x', 3, 'b']
print '[%s]' % ', '.join(map(str, mylist))
In Python 3 (where print is a builtin function and not a syntax feature anymore):
mylist = ['x', 3, 'b']
print('[%s]' % ', '.join(map(str, mylist)))
Both return:
[x...
How to sort a list of lists by a specific index of the inner list?
I have a list of lists. For example,
10 Answers
10
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How to use timeit module
...care is required so that one pass at an in-place sort doesn't affect the next pass with already sorted data (that, of course, would make the Timsort really shine because it performs best when the data already partially ordered).
Here is an example of how to set up a test for sorting:
>>> ...
Rotating and spacing axis labels in ggplot2
I have a plot where the x-axis is a factor whose labels are long. While probably not an ideal visualization, for now I'd like to simply rotate these labels to be vertical. I've figured this part out with the code below, but as you can see, the labels aren't totally visible.
...
WPF ListView turn off selection
...gt;
<ListView.ItemContainerStyle>
<Style TargetType="{x:Type ListViewItem}">
<Style.Triggers>
<Trigger Property="IsSelected"
Value="True">
<Setter Property="Background"
...
What is the difference between persist() and merge() in JPA and Hibernate?
...avadoc:
The semantics of the persist
operation, applied to an entity X are
as follows:
If X is a new entity, it
becomes managed. The entity X will be
entered into the database at or before
transaction commit or as a result of
the flush operation.
If X is a
preexisting ma...
How do you change Background for a Button MouseOver in WPF?
I have a button on my page with this XAML:
6 Answers
6
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How to append rows to an R data frame
...ined as:
# pre-allocate space
f3 <- function(n){
df <- data.frame(x = numeric(n), y = character(n), stringsAsFactors = FALSE)
for(i in 1:n){
df$x[i] <- i
df$y[i] <- toString(i)
}
df
}
Here's a similar approach, but one where the data.frame is created as the last step.
...