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Unresolved external symbol in object files
...ion. Solution was to add following preproc lines in every .h file:
#ifdef __cplusplus
extern "C"
{
#endif
and these in the end
#ifdef __cplusplus
}
#endif
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Standardize data columns in R
...
z = runif(10, 10, 20))
dat
dat2 <- dat %>% mutate_at(c("y", "z"), ~(scale(.) %>% as.vector))
dat2
which gives me this:
> dat
x y z
1 29.75859 3.633225 14.56091
2 30.05549 3.605387 12.65187
3 30.21689 3.318092 13.04672
4 29.53086 3.079992...
What techniques can be used to speed up C++ compilation times?
...more than once in a single translation unit.
#pragma once
#ifndef filename_h
#define filename_h
// Header declarations / definitions
#endif
By using both the pragma and the ifndef, you get the portability of the plain macro solution, as well as the compilation speed optimization that some compi...
Specifically, what's dangerous about casting the result of malloc?
... to prevent this error is mostly the same reasoning as writing
if (0 == my_var)
instead of
if (my_var == 0)
since the latter could lead to a serious bug if one would confuse = and ==, whereas the first one would lead to a compile error. I personally prefer the latter style since it better refl...
How do I keep Python print from adding newlines or spaces? [duplicate]
...
You can from __future__ import print_function in Python 2.6
– jfs
Nov 2 '08 at 18:10
14
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How to check Django version
... is as an executable command:
$ python -c "import django; print(django.get_version())"
2.0
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Bash empty array expansion with `set -u`
...4.4.
$ bash --version | head -n 1
GNU bash, version 4.4.19(1)-release (x86_64-pc-linux-gnu)
$ set -u
$ arr=()
$ echo "foo: '${arr[@]}'"
foo: ''
There is a conditional you can use inline to achieve what you want in older versions: Use ${arr[@]+"${arr[@]}"} instead of "${arr[@]}".
$ function ...
Change column type from string to float in Pandas
...
You have four main options for converting types in pandas:
to_numeric() - provides functionality to safely convert non-numeric types (e.g. strings) to a suitable numeric type. (See also to_datetime() and to_timedelta().)
astype() - convert (almost) any type to (almost) any other type ...
Detecting Unsaved Changes
...
Using jQuery:
var _isDirty = false;
$("input[type='text']").change(function(){
_isDirty = true;
});
// replicate for other input types and selects
Combine with onunload/onbeforeunload methods as required.
From the comments, the following ...
Real world use cases of bitwise operators [closed]
...r to make some piece of hardware do what you want it to:
volatile uint32_t *register = (volatile uint32_t *)0x87000000;
uint32_t value;
uint32_t set_bit = 0x00010000;
uint32_t clear_bit = 0x00001000;
value = *register; // get current value from the registe...