EDIT: This is now part of MoreLINQ. What you need is a “distinct-by” effectively. I don’t believe it’s part of LINQ as it stands, although it’s fairly easy to write: So to find the distinct values using just the Id property, you could use: And to use multiple properties, you can use anonymous types, which implement equality appropriately: … Read more
is the way to go. As the previous posters pointed out, paste can do two things: concatenate values into one “string”, e.g. where the argument sep specifies the character(s) to be used between the arguments to concatenate, or collapse character vectors where the argument collapse specifies the character(s) to be used between the elements of the vector to be … Read more
Rather than create 2 temporary dfs you can just pass these as params within a dict using the DataFrame constructor: There are lots of ways to construct a df, see the docs
The error you offer, error: expected initializer before ‘namespace’ suggests that there is a structure or variable declaration that isn’t terminated. Something like: Here, the ‘struct foo’ declaration isn’t terminated with a semicolon. This should read: Getting the preprocessor involved (using #include) makes this type of thing a bit harder to track down. It may be that … Read more
It’s a logical operator and can be used in any logical expression. http://php.net/manual/en/language.operators.logical.php
Firstly, you use both ar and arr, while arr is an array and ar is a list. This is both confusing to the reader and (it turns out) to the code author. In C++, std::list doesn’t have random access. You cannot use ar[], since operator[] is not defined for lists. Further, largestOfArray expects an array, not a list. You probably intended to use arr there instead of ar.
You can use \url
Try this: valgrind –leak-check=full -v ./your_program As long as valgrind is installed it will go through your program and tell you what’s wrong. It can give you pointers and approximate places where your leaks may be found. If you’re segfault’ing, try running it through gdb.
The “tiresome way” is standard SQL and how mainstream RDBMS do it. With a 100+ columns, you mostly likely have a design problem… also, there are mitigating methods in client tools (eg generation UPDATE statements) or by using ORMs
To reverse an int array, you swap items up until you reach the midpoint, like this: The way you are doing it, you swap each element twice, so the result is the same as the initial list.