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Dynamically select data frame columns using $ and a character value
...itten as
`$`(df , V1)
or indeed
`$`(df , "V1")
But...
`$`(df , paste0("V1") )
...for instance will never work, nor will anything else that must first be evaluated in the second argument. You may only pass a string which is never evaluated.
Instead use [ (or [[ if you want to extract only...
Cocoa: What's the difference between the frame and the bounds?
...
908
The bounds of an UIView is the rectangle, expressed as a location (x,y) and size (width,height)...
Removing leading zeroes from a field in a SQL statement
...ve the leading zeroes from a particular field, which is a simple VARCHAR(10) field. So, for example, if the field contains '00001A', the SELECT statement needs to return the data as '1A'.
...
What is the most efficient string concatenation method in python?
... |
edited May 11 '16 at 7:04
Quentin Pradet
4,28622 gold badges2626 silver badges4040 bronze badges
answ...
Are members of a C++ struct initialized to 0 by default?
... constructors
struct Snapshot {
int x;
double y;
Snapshot():x(0),y(0) { }
// other ctors / functions...
};
Will initialize both x and y to 0. Note that you can use x(), y() to initialize them disregarding of their type: That's then value initialization, and usually yields a proper...
SQL keys, MUL vs PRI vs UNI
...at column.
– pgoetz
Aug 7 '19 at 16:07
add a comment
|
...
Is “argv[0] = name-of-executable” an accepted standard or just a common convention?
When passing argument to main() in a C or C++ application, will argv[0] always be the name of the executable? Or is this just a common convention and not guaranteed to be true 100% of the time?
...
From ND to 1D arrays
...c = a.flatten()
If you just want an iterator, use np.ndarray.flat:
In [20]: d = a.flat
In [21]: d
Out[21]: <numpy.flatiter object at 0x8ec2068>
In [22]: list(d)
Out[22]: [1, 2, 3, 4, 5, 6]
share
|
...
JS Client-Side Exif Orientation: Rotate and Mirror JPEG Images
...erver or anything.
– igneosaur
May 20 '16 at 8:28
3
@igneosaur: you can send base64 encoded data ...
How to split a string and assign it to variables
...ort (
"fmt"
"strings"
)
func main() {
s := strings.Split("127.0.0.1:5432", ":")
ip, port := s[0], s[1]
fmt.Println(ip, port)
}
Output:
127.0.0.1 5432
One step, for example,
package main
import (
"fmt"
"net"
)
func main() {
host, port, err := net.SplitHostPort...