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Assign pandas dataframe column dtypes
... I've had to manually parse into a list of lists, as the file was not amenable for pd.read_csv )
6 Answers
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How to count the frequency of the elements in an unordered list?
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Note: You should sort the list before using groupby.
You can use groupby from itertools package if the list is an ordered list.
a = [1,1,1,1,2,2,2,2,3,3,4,5,5]
from itertools import groupby
[len(list(group)) for key, group in groupby(a)]
Output:
[4, 4...
O(nlogn) Algorithm - Find three evenly spaced ones within binary string
...thms test yesterday, and I can't figure out the answer. It is driving me absolutely crazy, because it was worth about 40 points. I figure that most of the class didn't solve it correctly, because I haven't come up with a solution in the past 24 hours.
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Is there a difference between using a dict literal and a dict constructor?
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I think you have pointed out the most obvious difference. Apart from that,
the first doesn't need to lookup dict which should make it a tiny bit faster
the second looks up dict in locals() and then globals() and the finds the builtin, so you can switch the beh...
Remove an item from a dictionary when its key is unknown
What is the best way to remove an item from a dictionary by value, i.e. when the item's key is unknown? Here's a simple approach:
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How to test if list element exists?
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This is actually a bit trickier than you'd think. Since a list can actually (with some effort) contain NULL elements, it might not be enough to check is.null(foo$a). A more stringent test might be to check that the name is actually defined in t...
Best way to represent a fraction in Java?
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It just so happens that I wrote a BigFraction class not too long ago, for Project Euler problems. It keeps a BigInteger numerator and denominator, so it'll never overflow. But it'll be a tad slow for a lot of operations that you know will never overflow.. a...
Find size of Git repository
... git 1.8.3 introduced a more efficient way to get a rough size: git count-objects -vH (see answer by @VonC)
For different ideas of "complete size" you could use:
git bundle create tmp.bundle --all
du -sh tmp.bundle
Close (but not exact:)
git gc
du -sh .git/
With the latter, you would also be...
How do I concatenate strings in Swift?
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You can concatenate strings a number of ways:
let a = "Hello"
let b = "World"
let first = a + ", " + b
let second = "\(a), \(b)"
You could also do:
var c = "Hello"
c += ", World"
I'm sure there are more ways too.
Bit of description
let creates a con...
javascript i++ vs ++i [duplicate]
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The difference between i++ and ++i is the value of the expression.
The value i++ is the value of i before the increment. The value of ++i is the value of i after the increment.
Example:
var i = 42;
alert(i++); // shows 42
alert(i); // sh...