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Selecting multiple columns in a pandas dataframe
...).
df1 = df[['a', 'b']]
Alternatively, if it matters to index them numerically and not by their name (say your code should automatically do this without knowing the names of the first two columns) then you can do this instead:
df1 = df.iloc[:, 0:2] # Remember that Python does not slice inclusive of...
The type or namespace name 'DbContext' could not be found [closed]
...t present even though the vs2010 Package Manager claimed I had 4.2.0.0 installed. With my project open in vs2010, running the install command via Tools, Library Package Manager, Package Manager Console added the reference to EntityFramework automatically and my subsequent build succeeded. thnx @Sh...
Building vs. Compiling (Java)
...
The "Build" is a process that covers all the steps required to create a "deliverable" of your software. In the Java world, this typically includes:
Generating sources (sometimes).
Compiling sources.
Compiling test sources.
Executing tests (unit tests, integrat...
MVC Vs n-tier architecture
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N-tier architecture usually has each layer separated by the network. I.E. the presentation layer is on some web servers, then that talks to backend app servers over the network for business logic, then that talks to a database server, again over t...
Stopwatch vs. using System.DateTime.Now for timing events [duplicate]
...time by counting timer ticks in the underlying timer mechanism. If the installed hardware and operating system support a high-resolution performance counter, then the Stopwatch class uses that counter to measure elapsed time. Otherwise, the Stopwatch class uses the system timer to measure elapsed ti...
Returning IEnumerable vs. IQueryable
...ecution.
The difference is that IQueryable<T> is the interface that allows LINQ-to-SQL (LINQ.-to-anything really) to work. So if you further refine your query on an IQueryable<T>, that query will be executed in the database, if possible.
For the IEnumerable<T> case, it will be L...
LINQ Single vs First
...should NOT use one, when you mean the other.
Note: In my code, I will typically use FirstOrDefault() and SingleOrDefault() but that's a different question.
Take, for example, a table that stores Customers in different languages using a Composite Key ( ID, Lang ):
DBContext db = new DBContext();
Cust...
How can I get list of values from dict?
...alues()) is the one way.
Yet, considering Python3, what is quicker?
[*L] vs. [].extend(L) vs. list(L)
small_ds = {x: str(x+42) for x in range(10)}
small_df = {x: float(x+42) for x in range(10)}
print('Small Dict(str)')
%timeit [*small_ds.values()]
%timeit [].extend(small_ds.values())
%timeit lis...
Angular JS break ForEach
...r for it does not break the forEach loop. It is merly a way to not execute all logic inside the loop.
– Nebulosar
Apr 8 at 13:42
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split string only on first instance - java
... length will be no greater than n, and the array's last entry will contain all input beyond the last matched delimiter.
The string boo:and:foo, for example, yields the following results with these parameters:
Regex Limit Result
: 2 { "boo", "and:foo" }
: 5 { "boo", "an...