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What's the difference between “groups” and “captures” in .NET regular expressions?
...bout it. Here's what the famous Jeffrey Friedl has to say about it (pages 437+):
Depending on your view, it either adds
an interesting new dimension to the
match results, or adds confusion and
bloat.
And further on:
The main difference between a Group
object and a Capture object is...
Return multiple values in JavaScript?
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1380
No, but you could return an array containing your values:
function getValues() {
return [...
Paste multiple columns together
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# your starting data..
data <- data.frame('a' = 1:3, 'b' = c('a','b','c'), 'c' = c('d', 'e', 'f'), 'd' = c('g', 'h', 'i'))
# columns to paste together
cols <- c( 'b' , 'c' , 'd' )
# create a new column `x` with the three columns collapsed together
data$x <- apply( d...
rails 3 validation on uniqueness on multiple attributes
I use Rails 3.0.0.beta4
3 Answers
3
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Javascript and regex: split string and keep the separator
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JonJon
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How to change the order of DataFrame columns?
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34 Answers
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typedef fixed length array
I have to define a 24-bit data type.I am using char[3] to represent the type. Can I typedef char[3] to type24 ? I tried it in a code sample. I put typedef char[3] type24; in my header file. The compiler did not complain about it. But when I defined a function void foo(type24 val) {} in my C...
Why is address zero used for the null pointer?
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edited May 3 '10 at 17:44
answered May 3 '10 at 17:22
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List comprehension vs map
...:
$ python -mtimeit -s'xs=range(10)' 'map(hex, xs)'
100000 loops, best of 3: 4.86 usec per loop
$ python -mtimeit -s'xs=range(10)' '[hex(x) for x in xs]'
100000 loops, best of 3: 5.58 usec per loop
An example of how performance comparison gets completely reversed when map needs a lambda:
$ pytho...
How to make a great R reproducible example
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23 Answers
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