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How is a CRC32 checksum calculated?
Maybe I'm just not seeing it, but CRC32 seems either needlessly complicated, or insufficiently explained anywhere I could find on the web.
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Is it worth using Python's re.compile?
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TriptychTriptych
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What's the difference between eval, exec, and compile?
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3 Answers
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Determining complexity for recursive functions (Big O notation)
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362
The time complexity, in Big O notation, for each function:
int recursiveFun1(int n)
{
if ...
How to find the sum of an array of numbers
Given an array [1, 2, 3, 4] , how can I find the sum of its elements? (In this case, the sum would be 10 .)
43 Answers
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What are the correct version numbers for C#?
...numbers for C#? What came out when? Why can't I find any answers about C# 3.5 ?
12 Answers
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Selecting data frame rows based on partial string match in a column
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How do I detect what .NET Framework versions and service packs are installed?
A similar question was asked here , but it was specific to .NET 3.5. Specifically, I'm looking for the following:
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Add Variables to Tuple
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388
Tuples are immutable; you can't change which variables they contain after construction. Howeve...
dplyr summarise: Equivalent of “.drop=FALSE” to keep groups with zero length in output
....drop argument that does just what you asked for:
df = data.frame(a=rep(1:3,4), b=rep(1:2,6))
df$b = factor(df$b, levels=1:3)
df %>%
group_by(b, .drop=FALSE) %>%
summarise(count_a=length(a))
#> # A tibble: 3 x 2
#> b count_a
#> <fct> <int>
#> 1 1 ...