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How to drop columns by name in a data frame
I have a large data set and I would like to read specific columns or drop all the others.
11 Answers
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Find value in an array
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I'm guessing that you're trying to find if a certain value exists inside the array, 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 A...
Is there a VB.NET equivalent for C#'s '??' operator?
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Use the If() operator with two arguments (Microsoft documentation):
' Variable first is a nullable type.
Dim first? As Integer = 3
Dim second As Integer = 6
' Variable first <> Nothing, so its value, 3, is returned.
Console...
What is the difference between Python's list methods append and extend?
What's the difference between the list methods append() and extend() ?
20 Answers
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Python multiprocessing pool.map for multiple arguments
...ort product
def merge_names(a, b):
return '{} & {}'.format(a, b)
if __name__ == '__main__':
names = ['Brown', 'Wilson', 'Bartlett', 'Rivera', 'Molloy', 'Opie']
with multiprocessing.Pool(processes=3) as pool:
results = pool.starmap(merge_names, product(names, repeat=2))
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How to dump a table to console?
...on: how do I go about installing an extension like pl.pretty? It's be nice if I could just do something like a gem install without futzing with unrolling tar balls and finding the ideal spot on my HD to situate things. Is there a quick/painless "do-it-this-way"?
– Cliff
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do N times (declarative syntax)
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If you're not interested in any arguments passed, use .forEach(something)
– kvsm
Jul 9 '18 at 0:44
a...
When is “i += x” different from “i = i + x” in Python?
I was told that += can have different effects than the standard notation of i = i + . Is there a case in which i += 1 would be different from i = i + 1 ?
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Is there a NumPy function to return the first index of something in an array?
...with first all the row indices, then all the column indices.
For example, if an array is two dimensions and it contained your item at two locations then
array[itemindex[0][0]][itemindex[1][0]]
would be equal to your item and so would
array[itemindex[0][1]][itemindex[1][1]]
numpy.where
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Flatten an Array of Arrays in Swift
Is there a counterpart in Swift to flatten in Scala, Xtend, Groovy, Ruby and co?
14 Answers
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