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Reshaping data.frame from wide to long format
...:
reshape(d,
direction = "long",
varying = list(names(d)[3:7]),
v.names = "Value",
idvar = c("Code", "Country"),
timevar = "Year",
times = 1950:1954)
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Reading binary file and looping over each byte
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396
Python 2.4 and Earlier
f = open("myfile", "rb")
try:
byte = f.read(1)
while byte != "...
How to display unique records from a has_many through relationship?
...ay to display unique records from a has_many, through relationship in Rails3.
4 Answers
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What is the difference between an expression and a statement in Python?
...duced to some kind of "value", which can be any Python object. Examples:
3 + 5
map(lambda x: x*x, range(10))
[a.x for a in some_iterable]
yield 7
Statements (see 1, 2), on the other hand, are everything that can make up a line (or several lines) of Python code. Note that expressions are stateme...
Python integer division yields float
...
Take a look at PEP-238: Changing the Division Operator
The // operator will be available to request floor division unambiguously.
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How to tell Maven to disregard SSL errors (and trusting all certs)?
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239
You can disable SSL certificate checking by adding one or more of these command line parameters...
What are the differences between vector and list data types in R?
...tors are "atomic vectors" in strict R parlance:
aaa <- vector("list", 3)
is.list(aaa) #TRUE
is.vector(aaa) #TRUE
Lists are a "recursive" type (of vector) whereas atomic vectors are not:
is.recursive(aaa) # TRUE
is.atomic(aaa) # FALSE
You process data objects with different functions...
ROW_NUMBER() in MySQL
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I want the row with the single highest col3 for each (col1, col2) pair.
That's a groupwise maximum, one of the most commonly-asked SQL questions (since it seems like it should be easy, but actually it kind of isn't).
I often plump for a null-self-join:
SELECT t0....
Formatting numbers (decimal places, thousands separators, etc) with CSS
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answered Oct 9 '18 at 21:32
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