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How to select the rows with maximum values in each group with dplyr? [duplicate]
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For me, it helped to count the number of values per group. Copy the count table into a new object. Then filter for the max of the group based on the first grouping characteristic. For example:
count_table <- df %>%
group_by(A, B) %>%
count() %>%
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Default height for section header in UITableView
I want to set the height of the first header in my UITableView. For the other headers I want them to remain the default height. What value/constant can I put in place of "someDefaultHeight" in the code below?
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Can you get the column names from a SqlDataReader?
...case unless I used quotes around the column name. SELECT id AS "MyId" FROM table;
– styfle
Jul 13 '13 at 0:02
sir its ...
A std::map that keep track of the order of insertion?
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You might combine a std::vector with a std::tr1::unordered_map (a hash table). Here's a link to Boost's documentation for unordered_map. You can use the vector to keep track of the insertion order and the hash table to do the frequent lookups. If you're doing hundreds of thousands of lookups,...
How to check if a function exists on a SQL database
...s for this type argument, particularly:
FN : Scalar function
IF : Inline table-valued function
TF : Table-valued-function
FS : Assembly (CLR) scalar-function
FT : Assembly (CLR) table-valued function
share
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Why are C# interface methods not declared abstract or virtual?
...phic with regards to the interface type, so it needs a slot on the virtual table to allow virtual method dispatching.
– Jordão
Sep 1 '10 at 20:06
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SQL Server: Difference between PARTITION BY and GROUP BY
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We can take a simple example.
Consider a table named TableA with the following values:
id firstname lastname Mark
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1 arun prasanth ...
How do you perform a left outer join using linq extension methods
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For a (left outer) join of a table Bar with a table Foo on Foo.Foo_Id = Bar.Foo_Id in lambda notation:
var qry = Foo.GroupJoin(
Bar,
foo => foo.Foo_Id,
bar => bar.Foo_Id,
(x,y) => new { Foo = x, Bars = y...
How to express a NOT IN query with ActiveRecord/Rails?
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Using Arel:
topics=Topic.arel_table
Topic.where(topics[:forum_id].not_in(@forum_ids))
or, if preferred:
topics=Topic.arel_table
Topic.where(topics[:forum_id].in(@forum_ids).not)
and since rails 4 on:
topics=Topic.arel_table
Topic.where.not(topics[:f...
Virtual member call in a constructor
...y are constructed, but start out as the most derived type, with the method table being for the most derived type. This means that virtual method calls always run on the most derived type.
When you combine these two facts you are left with the problem that if you make a virtual method call in a cons...