大约有 7,000 项符合查询结果（耗时：0.0207秒） [XML]
How can I check if a command exists in a shell script? [duplicate]
..., ksh or sh (as provided by dash), the following should work:
if ! type "$foobar_command_name" > /dev/null; then
# install foobar here
fi
For a real installation script, you'd probably want to be sure that type doesn't return successfully in the case when there is an alias foobar. In bash yo...
Get statistics for each group (such as count, mean, etc) using pandas GroupBy?
....475 -0.47
3 G H 1 1.480000 -0.630 -0.63
Footnotes
The code used to generate the test data is shown below:
In [1]: import numpy as np
...: import pandas as pd
...:
...: keys = np.array([
...: ['A', 'B'],
...: ['A', 'B'],
...: ...
How would you make a comma-separated string from a list of strings?
...
Why the map/lambda magic? Doesn't this work?
>>> foo = ['a', 'b', 'c']
>>> print(','.join(foo))
a,b,c
>>> print(','.join([]))
>>> print(','.join(['a']))
a
In case if there are numbers in the list, you could use list comprehension:
>>>...
JavaScript by reference vs. by value [duplicate]
...its properties - it adds
// a new property b[b.length] with the value "foo".
// So the object referenced by b has been changed.
b.push("foo");
// The "first" property of argument c has been changed.
// So the object referenced by c has been changed (unless c is a primitive)
c...
How does Haskell printf work?
... the Show class and just prints them:
{-# LANGUAGE FlexibleInstances #-}
foo :: FooType a => a
foo = bar (return ())
class FooType a where
bar :: IO () -> a
instance FooType (IO ()) where
bar = id
instance (Show x, FooType r) => FooType (x -> r) where
bar s x = bar (s &g...
Convert char to int in C#
...
This will convert it to an int:
char foo = '2';
int bar = foo - '0';
This works because each character is internally represented by a number. The characters '0' to '9' are represented by consecutive numbers, so finding the difference between the characters '0'...
Can you “ignore” a file in Perforce?
... I guess.
Assuming you have a client named "CLIENT", a directory named "foo" (located at your project root), and you wish to ignore all .dll files in that directory tree, you can add the following lines to your workspace view to accomplish this:
-//depot/foo/*.dll //CLIENT/foo/*.dll
-//depot/fo...
Assign one struct to another in C
...t this example :
The C code for a simple C program is given below
struct Foo {
char a;
int b;
double c;
} foo1,foo2;
void foo_assign(void)
{
foo1 = foo2;
}
int main(/*char *argv[],int argc*/)
{
foo_assign();
return 0;
}
The Equivalent ASM Code for foo_assign() is
00401...
Set a path variable with spaces in the path in a Windows .cmd file or batch file
...re the path unquoted and just quote it later:
set MyPath=C:\Program Files\Foo
"%MyPath%\foo with spaces.exe" something
Another option you could use is a subroutine which alles for un-quoting strings (but in this case it's actually not a very good idea since you're adding quotes, stripping them aw...
Is there a conditional ternary operator in VB.NET?
...able. Here's some more info: Visual Basic If announcement
Example:
Dim foo as String = If(bar = buz, cat, dog)
[EDIT]
Prior to 2008 it was IIf, which worked almost identically to the If operator described Above.
Example:
Dim foo as String = IIf(bar = buz, cat, dog)
...