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Why does SIGPIPE exist?
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Ton van den Heuvel
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answered Feb 18 '12 at 2:13
R.. GitHub STOP HELPING ICER.. GitHub...
Single Line Nested For Loops
...hension (here (x,y)):
>>> [(x, y) for x in [1,2,3] for y in [3,1,4] if x != y]
[(1, 3), (1, 4), (2, 3), (2, 1), (2, 4), (3, 1), (3, 4)]
It's exactly the same as this nested for loop (and, as the tutorial says, note how the order of for and if are the same).
>>> combs = []
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What is the most efficient way to create a dictionary of two pandas Dataframe columns?
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4 Answers
4
Active
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std::next_permutation Implementation Explanation
...td:next_permutation was implemented so I extracted the the gnu libstdc++ 4.7 version and sanitized the identifiers and formatting to produce the following demo...
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For each row return the column name of the largest value
...ample reproducible):
DF <- data.frame(V1=c(2,8,1),V2=c(7,3,5),V3=c(9,6,4))
colnames(DF)[apply(DF,1,which.max)]
[1] "V3" "V1" "V2"
A faster solution than using apply might be max.col:
colnames(DF)[max.col(DF,ties.method="first")]
#[1] "V3" "V1" "V2"
...where ties.method can be any of "rando...
How does numpy.histogram() work?
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edited Feb 4 '12 at 15:31
answered Feb 4 '12 at 15:09
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Select multiple columns in data.table by their numeric indices
... Henrik
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answered Nov 14 '12 at 17:28
Josh O'BrienJosh O'Brien
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Clojure: cons (seq) vs. conj (list)
...ts to insert into a collection, while cons takes just one:
(conj '(1 2 3) 4 5 6)
; => (6 5 4 1 2 3)
(cons 4 5 6 '(1 2 3))
; => IllegalArgumentException due to wrong arity
Another difference is in the class of the return value:
(class (conj '(1 2 3) 4))
; => clojure.lang.PersistentList
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How exactly does tail recursion work?
...lexey Frunze
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2
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How to select rows with one or more nulls from a pandas DataFrame without listing columns explicitly
I have a dataframe with ~300K rows and ~40 columns.
I want to find out if any rows contain null values - and put these 'null'-rows into a separate dataframe so that I could explore them easily.
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