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How to tell if a string is not defined in a Bash shell script
...
~> if [ -z $FOO ]; then echo "EMPTY"; fi
EMPTY
~> FOO=""
~> if [ -z $FOO ]; then echo "EMPTY"; fi
EMPTY
~> FOO="a"
~> if [ -z $FOO ]; then echo "EMPTY"; fi
~>
-z works for undefined variables too. To distinguish between...
variable === undefined vs. typeof variable === “undefined”
...
For undeclared variables, typeof foo will return the string literal "undefined", whereas the identity check foo === undefined would trigger the error "foo is not defined".
For local variables (which you know are declared somewhere), no such error would occu...
What are some examples of commonly used practices for naming git branches? [closed]
...roup tokens
Use "grouping" tokens in front of your branch names.
group1/foo
group2/foo
group1/bar
group2/bar
group3/bar
group1/baz
The groups can be named whatever you like to match your workflow. I like to use short nouns for mine. Read on for more clarity.
Short well-defined tokens
Choose...
How to check if a string starts with one of several prefixes?
I have the following if statement:
7 Answers
7
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Understanding PrimeFaces process/update and JSF f:ajax execute/render attributes
...certain command component is invoked ain't gonna work:
<p:inputText id="foo" value="#{bean.foo}" />
<p:commandButton process="foo" action="#{bean.action}" />
It would only process the #{bean.foo} and not the #{bean.action}. You'd need to include the command component itself as well:
<...
Easiest way to convert a List to a Set in Java
...
Set<Foo> foo = new HashSet<Foo>(myList);
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How to return a string value from a Bash function
... return.
#!/bin/bash
set -x
function pass_back_a_string() {
eval "$1='foo bar rab oof'"
}
return_var=''
pass_back_a_string return_var
echo $return_var
Prints "foo bar rab oof".
Edit: added quoting in the appropriate place to allow whitespace in string to address @Luca Borrione's comment.
E...
How to define an empty object in PHP
...e objects of anonymous type in JavaScript:
//JavaScript
var myObj = {
foo: "Foo value",
bar: "Bar value"
};
console.log(myObj.foo); //Output: Foo value
So I always try to write this kind of objects in PHP like javascript does:
//PHP >= 5.4
$myObj = (object) [
"foo" => "Foo valu...
How to access pandas groupby dataframe by key
...
You can use the get_group method:
In [21]: gb.get_group('foo')
Out[21]:
A B C
0 foo 1.624345 5
2 foo -0.528172 11
4 foo 0.865408 14
Note: This doesn't require creating an intermediary dictionary / copy of every subdataframe for every group, so will be muc...