How to convert a Dataset into an indexed dataset / association-of-associations given a column header?

Given a dataset as such


If "letter" is the header that is chosen, how do I convert it into an indexed dataset / association-of-associations?

i.e. How do I define f such that f[dataset_,columnHeader_] produces the following?

enter image description here

Please note GroupBy is close but fails as you are unable to use Part to work with the result to extract column data. eg:

data = {<|"letter" -> "a", "foo" -> 1, "bar" -> 2|>, <|"letter" -> "b", "foo" -> 3, "bar" -> 4|>, <|"letter" -> "c", "foo" -> 5, "bar" -> 6|>}; dataDS = Dataset[data]; dataDSg= GroupBy[dataDS, Key["letter"]]; dataDSg[All, "foo"] (* <- produces an error *) 

Where as data in the format of an association-of-association works fine

data2 = <|"a" -> <|"foo" -> 1, "bar" -> 2|>, "b" -> <|"foo" -> 3, "bar" -> 4|>, "c" -> <|"foo" -> 5, "bar" -> 6|>|>; data2DS = data2 // Dataset; data2DS [All, "foo"] (* <- returns a dataset with 1,3,5 *) 

I’v indexed my pages in search console, but Google didnt show them in search results [duplicate]

I have indexed all of my webpages into google search console tools.. but Google did not show the results in search results.

my website is :

Can you help me please.. see the latests articles, they wont show in search results

Thank you

Google Search Console not showing proper other pages results (they are indexed)

i have a website and than i have a wordpress blog in /blog route of that site they are kind of independent for now since i havent done any internal linking on them so i created this new post n my blog and submitted it for indexing it got positive results and its also showing up on google but i cant see its results on google search console does any one know why?

side note: i havent submitted site map for now.(and if its because of site map than is it possible to view results without sitemap?)

How is a symbol “given meaning by a family of operations indexed by symbols”?

Practical Foundation of Programming Languages by Harper says:

Chapter 31 Symbols

A symbol is an atomic datum with no internal structure. Whereas a variable is given meaning by substitution, a symbol is given meaning by a family of operations indexed by symbols. A symbol is just a name, or index, for a family of operations.

Many different interpretations may be given to symbols according to the operations we choose to consider, giving rise to concepts such as fluid binding, dynamic classification, mutable storage, and communication channels.

A type is associated to each symbol whose interpretation depends on the particular application. For example, in the case of mutable storage, the type of a symbol constrains the contents of the cell named by that symbol to values of that type.

What does “a symbol is given meaning by a family of operations indexed by symbols” mean? Is “a symbol” given meaning by a family of operations not one of the “symbols” indexing the family of operations? What is the relation between “a symbol” and “symbols”?

What does “a symbol is just a name, or index, for a family of operations” mean? Does it mean “a symbol names or indexes a family of operations”?

When a symbol is used in each of the following example cases (which I hope you could consider as many as possible, in particular the first three cases):

  • “represent a variable in symbolic representations of equations or programs” (see the quote below),
  • “represent a word in the representation of natural language sentences” (see the quote below),
  • represent an assignable (?) in mutable storage,
  • represent something (something similar to a variable?) in fluid binding,
  • represent a class (?) in dynamic classification,
  • represent something (?) in communication channels,

how does the above quote about a symbol applies, specifically:

  • is the symbol given meaning by what family of operations indexed by symbols?
  • is the symbol just a name, or index, for what family of operations?


The Scheme Programming Language, 4th Edition, by Dybvig, says

Section 2.2. Simple Expressions

Symbols and variables in Scheme are similar to symbols and variables in mathematical expressions and equations. When we evaluate the mathematical expression 1 – x for some value of x, we think of x as a variable. On the other hand, when we consider the algebraic equation x 2 – 1 = (x – 1)(x + 1), we think of x as a symbol (in fact, we think of the whole equation symbolically).

While symbols are commonly used to represent variables in symbolic representations of equations or programs, symbols may also be used, for example, as words in the representation of natural language sentences.