Hierarchical Todo List

• Classic Outline Format
• Basic Parts Of An Outline
• Examples Of Hierarchical Database
• Levels Of An Outline

This chapter considers hierarchical lists after the styleof the programming language Lisp.Where the lists of a previous chapterwere flat or one-level.Hierarchical lists contain both atomic elements and sublists.This allows them to store structured dataand they are general enough to be the only structured data type ofthe programming language Lisp.(Any serious computer scientist is strongly recommended to readThe LISP 1.5 Programmer's Manual by J. McCarthy et al,M.I.T. Press 1962.)

The direct answer to your question is that the list was likely created correctly, but you are not accessing it correctly. You access the nested lists like this: tree01. Tree01. However, you should use a dictionary, not a list. Format sd card macbook. It will make your look ups much more simple and they will be. I have in my document information organised hierarchically, as an indented bulleted list , with up to 10 levels of indentation.Due to the complexity of the structure of this list, it would be very helpful to be able to temporarily collapse low-level structures, and only see - at a glance - the top-level titles that contain them.

(It is also common to use 'curried' versions of functions especially in functional languages.)

There is a convention that lists do not terminate in an atom.This could be enforced by making cons(L,atom(e)) an error.

Most of the operations on flat lists also work on hierarchical lists.Note however that a sublist is considered to be an elementso that reversal of a list will not reverse its sublists.

The map function, as previously defined, applies a functionto every element of a list.There is no difficulty if those elements are themselves lists.

Hierarchical lists allow information with substructure to be stored.Some list operations are only applicable to hierarchical lists.For example, such a list can be flattened.

Note that this version of flatten potentially takes O(n²) time(exercise: why?).An O(n) version which does not use appendis possible using an accumulating parameter.

There are three alternative cases in the definition of the new list type -atomic, empty or non-empty.This means that most functions for manipulating listshave three cases in their definition.

If one of these cases is missing it is probably the sign of an error.The atomic and null cases are usually very simple, often returninga simple function of the atom or a constant value.This leaves only the constructed case.Here the result often involves a recursive call of the function onone or both of the sublists.As an example, consider counting the atoms in a list:Match this instance of a function against the general pattern given previously.

Implementation of Hierarchical Lists

The most natural way to implement the new list typeis with pointers and records although arrays can also be used.The empty list can be represented by the nil pointerbut there are two other cases and thesemust be implemented by a union.

There are two classes of node or cell in these lists;the tag `t' indicates the class of a cell.An atomic cell contains an element.A cons cell points to two sublists;by convention the second is always non-atomic.If this implementation can be assumed,it is faster to substitute in-line code for somethe basic operations rather than to call the routines.

Because a list structure can now contain sublists to an arbitrarydepth, printing a list becomes more complex.

Note that this routine uses a loop to iterate along the elements of the list.Recursion is used to print a sublist.The recursion can proceed to an arbitrary depth to matchthe list structure.

Because there is no implicit conversion from the element typeto an atomic list, it is necessary to have a routine to construct an atomiccell.This necessitates trivial changes to someof the routines previously defined on flat lists.For example, the sieve of Eratosthenes is given below in this new guise.

Lists and Trees

A (rooted) tree structure consists of nodes (or vertices)and arcs (or edges).A special ancestral node is called the root.An arc points from a parent node to each of its

Classic Outline Format

child nodes,if any.

© L . A l l i s o n

Trees can be used to represent hierarchical data,such as a business organisation.They share this ability with hierarchical lists andthe connection is much stronger; thereis a way of representing such a tree by a list.The technique is to link siblings together into a list.

Treesare very important in computing.A common type is the binary treewhere each node has at most two descendants;it is the subject of the next chapter.

Testing and Debugging

The techniques of testing and debugging that apply to flat listsare if anything even more useful in the case of hierarchical lists.Pre and postconditions and assertions should be used wherever possible.Flat lists can only have problems of contents and termination.A hierarchical list can also have problems of incorrect structure.For this reason an output routine is very important so as tobe able to print list values when things go wrong.

There are just three types of list -atomic, empty and non-empty.This realisation reduces the apparent complexity of listsand makes systematic testing and debugging possible.The key cases are an atom, nil, and a list of a 'few' elements.If a case is missing from a routine it probably indicates an error.Depending on the application,the third case may include a small number ofexamples of different nesting structure. Sims 4 how to use the book of life.

For example, we might have written the following incorrect functionto count the atoms in a list:

Testing on [1,2,3,4] would give the correct answer 4.Testing on [1,[2,3],4] would produce the incorrect answer 3 rather thanthe correct answer 4 and a diagnosis should easily follow.Care is needed however because testing on [1,[2],3,4] would not showthe error up.

In general, testing can show a program to be wrong but cannever prove it to be correct.Nevertheless judicious testing as an adjunct to program verificationcan add to confidence in a program.Matching test cases to the structure of a data typeand to the structure of the routines acting on it leads to fastsystematic testing and debugging.

Exercises

1. An element at the top level of a list is said to be at a depth of 1.If L' is a sublist at depth 1 of L and x is at depth d of L'then x is at depth d+1 of L.Write a function to find the depth of the deepest element of a list.
2. Write a routine to `reflect' a hierarchical list so thatthe list and all sublists are reversed as if seen in a mirror.
3. Write a fast O(n) time routine to flatten a hierarchical list of n cells.
   eg. flatten [1, [[2, 3], 4], 5] = [1, 2, 3, 4, 5].
4. Use a hierarchical list to represent the structure of (part of)your university or institute.This may contain faculties, schools and departments orperhaps it has other 'layers'.It will probably be necessary to add extra information fields tothe list cells.
5. Modify the routine that prints a list sothat it makes use of indentation to representsublist structure.Note that there is no single best answer to this problem;the ideal style is a matter of taste.
6. Convert the list printing routine, PutList, into iterative,non-recursive form.

© L.Allison,Department of Computer Science, UWA 1984-86.

A list displays a set of records from a table.

Users can search, sort, filter, and edit data in lists. Lists may be embedded in forms and may be hierarchical (have sublists).

The list interface consists of a title bar, filters and breadcrumbs, columns of data, and a footer. Each column in a list corresponds to a field on the table.

Watch the twelve-minute video User Interface | Getting Started with Lists for an in-depth introduction to list functionality.

A response time indicator () may appear at the bottom right of some lists to indicate the processing time required to display the list.

There are two versions of lists available. Companies with large or complex datasets, or those accustomed to the features in List v2 should avoid activating the list v3 plugin. For more information, see Comparison of List v2 and List v3.

List features and actions

The list interface consists of a title bar, filters and breadcrumbs, and columns of data. Each of these components provides features and lets you act on the list and the displayed records. There are two list versions: List v2 and List v3.

Hierarchical lists

Hierarchical lists allow users to view records from related lists directly from a v2 list without navigating to a form.

Basic Parts Of An Outline

Lists can have sublists in a hierarchy that can also be accessed in list view. To expand or collapse the related lists on a record in a hierarchical list, click the arrow () beside the reference icon.

Administrators can enable hierarchical lists for a table. Bettertouchtool 2 318 – customize multi touch trackpad gestures copy. For more information, see Enable a hierarchical list .

Examples Of Hierarchical Database

Detail rows

Levels Of An Outline

Trees can be used to represent hierarchical data,such as a business organisation.They share this ability with hierarchical lists andthe connection is much stronger; thereis a way of representing such a tree by a list.The technique is to link siblings together into a list.

Treesare very important in computing.A common type is the binary treewhere each node has at most two descendants;it is the subject of the next chapter.

Testing and Debugging

The techniques of testing and debugging that apply to flat listsare if anything even more useful in the case of hierarchical lists.Pre and postconditions and assertions should be used wherever possible.Flat lists can only have problems of contents and termination.A hierarchical list can also have problems of incorrect structure.For this reason an output routine is very important so as tobe able to print list values when things go wrong.

There are just three types of list -atomic, empty and non-empty.This realisation reduces the apparent complexity of listsand makes systematic testing and debugging possible.The key cases are an atom, nil, and a list of a 'few' elements.If a case is missing from a routine it probably indicates an error.Depending on the application,the third case may include a small number ofexamples of different nesting structure. Sims 4 how to use the book of life.

For example, we might have written the following incorrect functionto count the atoms in a list:

Testing on [1,2,3,4] would give the correct answer 4.Testing on [1,[2,3],4] would produce the incorrect answer 3 rather thanthe correct answer 4 and a diagnosis should easily follow.Care is needed however because testing on [1,[2],3,4] would not showthe error up.

In general, testing can show a program to be wrong but cannever prove it to be correct.Nevertheless judicious testing as an adjunct to program verificationcan add to confidence in a program.Matching test cases to the structure of a data typeand to the structure of the routines acting on it leads to fastsystematic testing and debugging.

Exercises

1. An element at the top level of a list is said to be at a depth of 1.If L' is a sublist at depth 1 of L and x is at depth d of L'then x is at depth d+1 of L.Write a function to find the depth of the deepest element of a list.
2. Write a routine to `reflect' a hierarchical list so thatthe list and all sublists are reversed as if seen in a mirror.
3. Write a fast O(n) time routine to flatten a hierarchical list of n cells.
   eg. flatten [1, [[2, 3], 4], 5] = [1, 2, 3, 4, 5].
4. Use a hierarchical list to represent the structure of (part of)your university or institute.This may contain faculties, schools and departments orperhaps it has other 'layers'.It will probably be necessary to add extra information fields tothe list cells.
5. Modify the routine that prints a list sothat it makes use of indentation to representsublist structure.Note that there is no single best answer to this problem;the ideal style is a matter of taste.
6. Convert the list printing routine, PutList, into iterative,non-recursive form.

© L.Allison,Department of Computer Science, UWA 1984-86.

A list displays a set of records from a table.

Users can search, sort, filter, and edit data in lists. Lists may be embedded in forms and may be hierarchical (have sublists).

The list interface consists of a title bar, filters and breadcrumbs, columns of data, and a footer. Each column in a list corresponds to a field on the table.

Watch the twelve-minute video User Interface | Getting Started with Lists for an in-depth introduction to list functionality.

A response time indicator () may appear at the bottom right of some lists to indicate the processing time required to display the list.

There are two versions of lists available. Companies with large or complex datasets, or those accustomed to the features in List v2 should avoid activating the list v3 plugin. For more information, see Comparison of List v2 and List v3.

List features and actions

The list interface consists of a title bar, filters and breadcrumbs, and columns of data. Each of these components provides features and lets you act on the list and the displayed records. There are two list versions: List v2 and List v3.

Hierarchical lists

Hierarchical lists allow users to view records from related lists directly from a v2 list without navigating to a form.

Basic Parts Of An Outline

Lists can have sublists in a hierarchy that can also be accessed in list view. To expand or collapse the related lists on a record in a hierarchical list, click the arrow () beside the reference icon.

Administrators can enable hierarchical lists for a table. Bettertouchtool 2 318 – customize multi touch trackpad gestures copy. For more information, see Enable a hierarchical list .

Examples Of Hierarchical Database

Detail rows

Levels Of An Outline

Detail rows, when enabled, appear below the field row for each record and display the value of a specified field. For example, the detail row might display the short description for each incident in a list. Detail rows support the same functionality as fields, including links, editing capabilities, and access to the context menu.

Ios dev center apple developer. Administrators can enable detail rows and add them to v2 lists (UI15 or later required). For more information, see Administer detail rows. Detail rows are not supported in List v3.