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Remove all occurrences of a value from a list?
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23 Answers
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Compare two data.frames to find the rows in data.frame 1 that are not present in data.frame 2
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13 Answers
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Accessing items in an collections.OrderedDict by index
...oo', 'python')
>>> d.items()[1]
('bar', 'spam')
Note for Python 3.X
dict.items would return an iterable dict view object rather than a list. We need to wrap the call onto a list in order to make the indexing possible
>>> items = list(d.items())
>>> items
[('foo', 'pyth...
Find value in an array
...rray, and if that's the case, you can use Array#include?(value):
a = [1,2,3,4,5]
a.include?(3) # => true
a.include?(9) # => false
If you mean something else, check the Ruby Array API
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How to access the ith column of a NumPy multidimensional array?
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>>> test[:,0]
array([1, 3, 5])
Similarly,
>>> test[1,:]
array([3, 4])
lets you access rows. This is covered in Section 1.4 (Indexing) of the NumPy reference. This is quick, at least in my experience. It's certainly much quicker tha...
How do I declare and initialize an array in Java?
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2737
You can either use array declaration or array literal (but only when you declare and affect the...
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Using async/await for multiple tasks
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int[] ids = new[] { 1, 2, 3, 4, 5 };
Parallel.ForEach(ids, i => DoSomething(1, i, blogClient).Wait());
Although you run the operations in parallel with the above code, this code blocks each thread that each operation runs on. For example, if the ...
How does one reorder columns in a data frame?
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354
Your dataframe has four columns like so df[,c(1,2,3,4)].
Note the first comma means keep all t...
Automatically expanding an R factor into a collection of 1/0 indicator variables for every factor le
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131
Use the model.matrix function:
model.matrix( ~ Species - 1, data=iris )
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