TODO.md

In decisionpatterns/r-hash: A Hash/Dictionary/Map/Associated Array for R

TODO:

• [] fix argument order has.key(x, hash) to has_key(hash,x)

• [] Fix behavior on values to reduce and retain class

• implement drop argument? Is there a use case when drop would reduce the object to something other than a hash?

• implement mget in slice operation

• Create a mapping from Python's dictionary to hash package c.f. http://docs.python.org/2/library/stdtypes.html#dictionary-view-objects

• automatic coercion for hash[ x , ... ] where x is a 'name'

• Is there a happly function that is like lapply that either passes keys and values to the functions happly( h, function(k,v,...) ), will it return a hash object?

• [x] Increase perfomance of [ and hash methods

• [x] Be able to create a loop that assigns both key and value, e.g.: for( k,v in ha ) ...

  • use itertools to iterate over keys and values

Defaults

• (LOW PRIORITY) default MISSING behavior should be customizable at the hash instance level. Requires a slot: @na.action that can be a function or value. This default should exist between the global default and the call level. This is low priority since missing customization only applies to hash slices now.

x Default of missing key should be NULL. - option to fail on missing key? - customizable missing

• Should the default value of non-existant keys be NA or NULL.

  • The default of the environemnet is NULL
  • NA is the norm when data is missing, i.e. from a frame.
  • N.B. When access these objects the missing values are returned:
  • vectors : NA
  • list : NULL
  • data.frames : NULL
  • since getOption( 'na.action.hash' ) returns NULL if undefined, we can use this as getOption( 'na.action.hash' ) as the na.action only . . . but this sets the value of the Hash to NULL. Setting the value to NULL is equal to deleting the key. h$key <- NULL deletes the key.

• [x] Handle any type for a key, especially integers.

• [?] Keep track of the type of the key: [e-mail] Asking for keys(h) would return the original type via coercion.

• [x] Method to coerce value to key even through the make.key or make.name functions. ? Do we allow mixing of types ? :: NO

• [?] IxHash : Indexed Hash. Allow access by integer position? There becomes a problem of keeping track of replacements.

• [ ] Keys can have muliple values / be recursive? how would this be implemented as an md5hash of the args? h[[ vector ]] <- values ? h[[ paste( as.character( vector ) ) ]] <- value How can we make each of the keys searchable? i.e. get all where the second key field = 7. Each of the key fields would have to be hashed?

• Coersion functions

  • as.vector,
  • pairlist,
  • [x] as.data.frame,
  • [x] as.environment,
  • [x] as.list

• other coercions : as.environment, not possible without clobbering base h@env anyhow as.vector , yes

• Implement clear as initializing of hash rather than rm

• R/clear.R bug? :: SHOULD THIS COPY THE HASH? h <- hash( letters, 1:26 ) hh <- h clear(hh) h # EMPTY.

  Does not work the same with 'rm'. Will this require overloading the assignment operators?

• test functions x is.hash : object is a hash is.vector : test values to see if they are expressible as a vector is.list : "

• assign <==> set : it is to bad that assign is used instead of get get/set seems better aligned than get/assign.

decisionpatterns/r-hash documentation built on Feb. 6, 2019, 10:27 p.m.