data elementsIt can be composed of several data items, which are data itemsIndivisibleThe smallest unit of cutting.The name of data item includes number, alias, brief description, length, type andValue range。data itemyesdata recordThe most basic and indivisible famousData unit, is the smallest identification unit with independent meaning.
Data items can be letters, numbers, or a combination of both.adoptdata type(logical, numerical, character, etc.) and data length.Data items are used to describe certain attributes of an entity.stayGeographic Information SystemIn, the data item description object isGeographical entityElements and their attributes are divided into geometric attributes（geographical positionAnd shape) and non geometric attributes, includingscalarAttributes (various measured values) and name attributes (place names and figure names).
Differential connection
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computer data
computer data
DataData is the carrier of information.It can be recognized, stored and processed by computers. It is a computerprogramProcessed "raw materials".With the computerapplication area Expansion of.
The scope of data includes: integer, real numbercharacter string, images, sounds, etc.
Soft Way Quotes
data item: Data Item ispowerdesignerThe attribute template provided in.
data elements
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Data element concept
data elements(Data Element) is dataBasic unit。data elementsAlso called element, node, vertex and record.A data element can be composed of several data items (also called fields, fields, and attributes).
data(data) Yesobjective thingsThe symbol ofGraphical symbols, numbers, letters, etc.In other words, data are facts and concepts obtained through physical observation, and are descriptions of places, events, other objects or concepts in the real world.
Computer Data Elements
staycomputer scienceData refers to all data that can be input intocomputerThe general term for the medium of symbols processed by computer programs, which is used to input numbers, letters, symbols andAnalog quantityA general term for.It is the most basic element of geographic information system.
② Qualitative, such as data representing the attributes of things（Residential area, rivers, roads, etc.);
③ Quantitative data reflecting the quantitative characteristics of things, such as length, area, volume, etcGeometric quantityOr weight, speed, etcphysical quantity；④Data reflecting the time characteristics of things, such asYear, month, day, hour, minute, second, etc.
Classification of manifestations
It can be divided into:
①digital data, such as various statistical or measurement data;
②Analog data, bycontinuous function Composition, also divided intographic data (such as point, line, face), symbol data, text data, andimage dataEtc.PressRecord modeIt is divided into maps, tables, images, tapes and paper tapes.Divided intovector data 、Grid data Etc.In GIS, data selection, type, quantity, collection method, detail levelreliabilityEtc., depending onSystem applicationObjective, function, structure and data processing, management and analysis requirements.
