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Getting a map() to return a list in Python 3.x
...ases, this ends up saving memory, and should make things go faster.
If all you're going to do is iterate over this list eventually, there's no need to even convert it to a list, because you can still iterate over the map object like so:
# Prints "ABCD"
for ch in map(chr,[65,66,67,68]):
prin...
What is the difference between Ruby 1.8 and Ruby 1.9
... Sam's slides. The slideshow is less overwhelming to review, but having it all laid out in a list like this is also helpful.
Ruby 1.9 - Major Features
Performance
Threads/Fibers
Encoding/Unicode
gems is (mostly) built-in now
if statements do not introduce scope in Ruby.
What's changed?
Single ...
Using reflect, how do you set the value of a struct field?
...rue if the value's
address can be obtained with Addr.
Such values are called addressable. A
value is addressable if it is an
element of a slice, an element of an
addressable array, a field of an
addressable struct, or the result of
dereferencing a pointer. If CanAddr
returns false, c...
Generate a random double in a range
...
This is generally correct, but beware of its limits. If you do double rangeMax= Double.MAX_VALUE; and double rangeMin= -rangeMax; you will always get an infinite value in return. You might want to check for Double.valueOf(rangeMax-range...
What jsf component can render a div tag?
...if you want to wrap any of your JSF code with the div tag.
Alternatively, all the major UI Frameworks have a div component tag, or you could write your own.
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Numpy - add row to array
...2, 0]])
X = array([[0, 1, 2], [1, 2, 0], [2, 1, 2], [3, 2, 0]])
add to A all rows from X where the first element < 3:
import numpy as np
A = np.vstack((A, X[X[:,0] < 3]))
# returns:
array([[0, 1, 2],
[0, 2, 0],
[0, 1, 2],
[1, 2, 0],
[2, 1, 2]])
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Python regular expressions return true/false
...sing Python regular expressions how can you get a True / False returned? All Python returns is:
6 Answers
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Rails 3 check if attribute changed
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Check out ActiveModel::Dirty (available on all models by default). The documentation is really good, but it lets you do things such as:
@user.street1_changed? # => true/false
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Checkbox for nullable boolean
...iad of different reasons why the foo input might not appear on the page at all. If it does appear I can assume there's a value, but I need to be able to differentiate between when the model is posted with foo as unchecked and when foo isn't shown.
– DMulligan
J...
Is there a way to iterate over a slice in reverse in Go?
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Ulf Holm NielsenUlf Holm Nielsen
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