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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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Return multiple values in JavaScript?
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1380
No, but you could return an array containing your values:
function getValues() {
return [...
rails 3 validation on uniqueness on multiple attributes
I use Rails 3.0.0.beta4
3 Answers
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Search for string and get count in vi editor
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edited Jun 3 '15 at 9:51
Martin Tournoij
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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$x <- apply( d...
List comprehension vs map
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$ 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...
Difference between map, applymap and apply methods in Pandas
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Straight from Wes McKinney's Python for Data Analysis book, pg. 132 (I highly recommended this book):
Another frequent operation is applying a function on 1D arrays to each column or row. DataFrame’s apply method does exactly this:
In [116]: frame = DataFrame(np.random.randn(4, 3),...
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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