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What does [:] mean?
...at they want with the slice.
In the context of:
x = obj[:]
This will call obj.__getitem__ with the slice object passed in. In fact, this is completely equivalent to:
x = obj[slice(None,None,None)]
(although the former is probably more efficient because it doesn't have to look up the slice ...
How to get the last N rows of a pandas DataFrame?
...7 c 8
df[-3:]
A B
5 b 6
6 b 7
7 c 8
This is the same as calling df.iloc[-3:], for instance (iloc internally delegates to __getitem__).
As an aside, if you want to find the last N rows for each group, use groupby and GroupBy.tail:
df.groupby('A').tail(2)
A B
1 a 2
2 a ...
How to import an excel file in to a MySQL database
...
There's a simple online tool that can do this called sqlizer.io.
You upload an XLSX file to it, enter a sheet name and cell range, and it will generate a CREATE TABLE statement and a bunch of INSERT statements to import all your data into a MySQL database.
(Disclaim...
Access Control Request Headers, is added to header in AJAX request with jQuery
...
Here is an example how to set a request header in a jQuery Ajax call:
$.ajax({
type: "POST",
beforeSend: function(request) {
request.setRequestHeader("Authority", authorizationToken);
},
url: "entities",
data: "json=" + escape(JSON.stringify(createRequestObject)),
process...
How do you manually execute SQL commands in Ruby On Rails using NuoDB
...cords found and if there is none, it will return nil.
This way I can just call it anywhere on the rails application like for example:
records = execute_statement("select * from table")
"execute_statement" can also call NuoDB procedures, functions, and also Database Views.
...
How can I tell if I'm running in 64-bit JVM or 32-bit JVM (from within a program)?
... tell if the JVM in which my application runs is 32 bit or 64-bit? Specifically, what functions or properties I can used to detect this within the program?
...
Does Java casting introduce overhead? Why?
... casting, when you cast from a type to a wider type, which is done automatically and there is no overhead:
String s = "Cast";
Object o = s; // implicit casting
Explicit casting, when you go from a wider type to a more narrow one. For this case, you must explicitly use casting like that:
Object o...
Is there a git-merge --dry-run option?
... operation? It says "all conflicts are fixed but you are still merging". Calling git checkout . doesn't revert the files to pre-merge status.
– J-bob
Dec 8 '14 at 16:38
2
...
How to pull remote branch from somebody else's repo
...ict with one of your own branches is bothersome. In that case, a reference called FETCH_HEAD is available. You can git log FETCH_HEAD to see their commits then do things like cherry-picked to cherry pick their commits.
Pushing it back to them:
Oftentimes, you want to fix something of theirs and p...
Folder structure for a Node.js project
...amework like express or mongoose):
/models contains all your ORM models (called Schemas in mongoose)
/views contains your view-templates (using any templating language supported in express)
/public contains all static content (images, style-sheets, client-side JavaScript)
/assets/images contains...