大约有 45,000 项符合查询结果（耗时：0.0189秒） [XML]
how do I insert a column at a specific column index in pandas?
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388
see docs: http://pandas.pydata.org/pandas-docs/stable/generated/pandas.DataFrame.insert.html
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Implementing slicing in __getitem__
...m__(self, val):
... print val
...
>>> c = C()
>>> c[3]
3
>>> c[3:4]
slice(3, 4, None)
>>> c[3:4:-2]
slice(3, 4, -2)
>>> c[():1j:'a']
slice((), 1j, 'a')
share
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Turn off CSRF token in rails 3
...that I see here in stackoverflow but it seems they no longer work on rails 3.
3 Answers
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Why does SIGPIPE exist?
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edited Oct 26 '16 at 9:13
Ton van den Heuvel
8,39155 gold badges3434 silver badges7575 bronze badges
a...
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...
Is there an R function for finding the index of an element in a vector?
... function match works on vectors :
x <- sample(1:10)
x
# [1] 4 5 9 3 8 1 6 10 7 2
match(c(4,8),x)
# [1] 1 5
match only returns the first encounter of a match, as you requested. It returns the position in the second argument of the values in the first argument.
For multiple matching, ...
Callback functions in C++
...pe.
X.2 "Calling" a callback refers to the syntax to call those objects.
X.3 "Using" a callback means the syntax when passing arguments to a function using a callback.
Note: As of C++17, a call like f(...) can be written as std::invoke(f, ...) which also handles the pointer to member case.
1. Fun...
R - Concatenate two dataframes?
...olumn b to data frame b.
Results
> a <- data.frame(a=c(0,1,2), b=c(3,4,5), c=c(6,7,8))
> a
a b c
1 0 3 6
2 1 4 7
3 2 5 8
> b <- data.frame(a=c(9,10,11), c=c(12,13,14))
> b
a c
1 9 12
2 10 13
3 11 14
> b$b <- NA
> b
a c b
1 9 12 NA
2 10 13 NA
3 11 14 NA
> ...