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Way to read first few lines for pandas dataframe
...d of time? I have a large file that takes a long time to read, and occasionally only want to use the first, say, 20 lines to get a sample of it (and prefer not to load the full thing and take the head of it).
...
Convert pandas dataframe to NumPy array
...p.nan)
# array([ 1., 2., nan])
This is called out in the docs.
If you need the dtypes...
As shown in another answer, DataFrame.to_records is a good way to do this.
df.to_records()
# rec.array([('a', -1, 4), ('b', 2, 5), ('c', 3, 6)],
# dtype=[('index',...
Finding differences between elements of a list
...
Actually simply list(map(operator.sub, t[1:], t[:-1])) will do.
– blhsing
Aug 6 '18 at 15:24
add a comme...
What is NODE_ENV and how to use it in Express?
...ment variable and do different things based on the value. NODE_ENV specifically is used (by convention) to state whether a particular environment is a production or a development environment. A common use-case is running additional debugging or logging code if running in a development environment.
A...
How to parse JSON data with jQuery / JavaScript?
I have a AJAX call that returns some JSON like this:
10 Answers
10
...
Create a nonclustered non-unique index within the CREATE TABLE statement with SQL Server
...ne index create option:
CREATE TABLE MyTable(
a int NOT NULL
,b smallint NOT NULL
,c smallint NOT NULL
,d smallint NOT NULL
,e smallint NOT NULL
-- This creates a primary key
,CONSTRAINT PK_MyTable PRIMARY KEY CLUSTERED (a)
-- This creates a unique nonclustered ind...
PreparedStatement IN clause alternatives?
... FROM my_table WHERE search_column = ? ; ... and execute it. [Or use UNION ALL in place of those semicolons. --ed] Requires one prepared statement per size-of-IN-list. Stupidly slow, strictly worse than WHERE search_column IN (?,?,?), so I don't know why the blogger even suggested it.
Use a stored p...
cannot load such file — bundler/setup (LoadError)
...
It could be that there was a previous Ruby env installed on your system prior to your installation of 2.0? This might have had an existing GEM_PATH that lead to the /1.8 directory which the installation of version 2.0 simply kept.
The problem you where likely having, then, ...
Copy the entire contents of a directory in C#
...
Much easier
//Now Create all of the directories
foreach (string dirPath in Directory.GetDirectories(SourcePath, "*",
SearchOption.AllDirectories))
Directory.CreateDirectory(dirPath.Replace(SourcePath, DestinationPath));
//Copy all the files...
What's Pros and Cons: putting javascript in head and putting just before the body close
...p Your Web Site:
The problem caused by scripts is that
they block parallel downloads. The
HTTP/1.1 specification suggests that
browsers download no more than two
components in parallel per hostname.
If you serve your images from multiple
hostnames, you can get more than two
downloa...