大约有 42,000 项符合查询结果（耗时：0.0422秒） [XML]
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...
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.
share
|
...
How to tell Maven to disregard SSL errors (and trusting all certs)?
...
239
You can disable SSL certificate checking by adding one or more of these command line parameters...
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)
share
|
...
What is the purpose of the EBP frame pointer register?
...
|
edited Sep 13 '17 at 18:21
answered Feb 23 '09 at 20:55
...
urllib2.HTTPError: HTTP Error 403: Forbidden
...
3 Answers
3
Active
...
How to use arguments from previous command?
...w see:
$ echo a
without pressing Enter yet, do the following
Press Alt-3 Alt-Ctrl-y
Press Alt-- 2 Alt-Ctrl-y
Now you will see:
$ echo ace
By the way, you could have put the echo on the line by selecting argument 0:
Press Alt-0 Alt-Ctrl-y
Edit:
To answer the question you added to your or...
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...
Why aren't python nested functions called closures?
...
403
A closure occurs when a function has access to a local variable from an enclosing scope that has...
ROW_NUMBER() in MySQL
...
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....