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How to form tuple column from two columns in Pandas
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edited Nov 7 '16 at 16:58
answered Apr 17 '13 at 19:24
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Does the ternary operator exist in R?
... returns the latest evaluation, if-else is equivalent to ?:.
> a <- 1
> x <- if(a==1) 1 else 2
> x
[1] 1
> x <- if(a==2) 1 else 2
> x
[1] 2
The power of R is vectorization. The vectorization of the ternary operator is ifelse:
> a <- c(1, 2, 1)
> x <- ifelse(a=...
Get operating system info
...that, it sniffs your core operating system model, for example windows nt 5.1 as my own.
It then passes windows nt 5.1/i to Windows XP as the operating system.
Using: '/windows nt 5.1/i' => 'Windows XP', from an array.
You could say guesswork, or an approximation yet nonetheless pretty much ba...
SQL Logic Operator Precedence: And and Or
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And has precedence over Or, so, even if a <=> a1 Or a2
Where a And b
is not the same as
Where a1 Or a2 And b,
because that would be Executed as
Where a1 Or (a2 And b)
and what you want, to make them the same, is the following (using parentheses to override rule...
How to check whether a pandas DataFrame is empty?
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edited Dec 15 '17 at 17:37
Dave Thomas
1,38922 gold badges1010 silver badges1616 bronze badges
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Clojure: cons (seq) vs. conj (list)
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150
One difference is that conj accepts any number of arguments to insert into a collection, while...
What are the aspect ratios for all Android phone and tablet devices?
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162
In case anyone wanted more of a visual reference:
Decimal approximations reference table:
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How to split a string in shell and get the last field
Suppose I have the string 1:2:3:4:5 and I want to get its last field ( 5 in this case). How do I do that using Bash? I tried cut , but I don't know how to specify the last field with -f .
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Select multiple columns in data.table by their numeric indices
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185
For versions of data.table >= 1.9.8, the following all just work:
library(data.table)
dt &...
Time complexity of Sieve of Eratosthenes algorithm
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118
Your n/2 + n/3 + n/5 + … n/97 is not O(n), because the number of terms is not constant. [Ed...