Mapping EDI, NEON and DataONE units to the QUDT ontology, 2022

In the metadata of digital environmental datasets, automated processing is hindered by the wide variety of representations for unit that may be human-readable, but may not be unambiguous or machine-interpretable, (e.g., grams per square meter, gm/m2, g/m2, gm-2, g/m^2, g.m-2, g m-2 and gramPerMeterSquared). Matching disparate representations of the same unit into a single unit concept from an ontology assists with interpretation and reuse by providing a linkage to a complete unit definitions with label, description, dimensions. Datasets with shared units can be identified during searches, and are more suitable for automating analyses and potential transformation. This dataset contains data and code associated with a project to map units in ecological metadata collected between 2013 and 2022 by DataONE, the Environmental Data Initiative and the U.S. National Ecological Observatory Network to the QUDT ontology using successive string transformations. Data entities include a) raw metadata as received (355,057 unit instances) b) integrated raw data c) substitution tables for string transformations d) resulting lookup table for 896 distinct units matched to QUDT units e) associated R code used for QUDT matching plus a web service and R functions for adding annotation elements to Ecological Metadata Language metadata documents. Using these substitutions and code, 91% of unit instances in the raw metadata could be matched to QUDT. Data and results are discussed in “Porter JH, M O’Brien, M Frants, S Earl, M Martin, C Laney. (in review) Using a Units Ontology to Annotate Pre-Existing Metadata. Submitted to Scientific Data.在数字环境数据集的元数据中，自动化处理流程常因单位的多样化表述形式而受阻——这类表述虽具备人类可读性，但往往缺乏明确性，亦无法被机器直接解析（例如克每平方米的表述形式包括grams per square meter、gm/m2、g/m2、gm-2、g/m^2、g.m-2、g m-2以及gramPerMeterSquared）。将同一单位的不同表述匹配至本体中的单一单位概念，可通过关联完整的单位定义（含标签、描述与量纲）辅助解读与复用。可在检索阶段识别出共享相同单位的数据集，此类数据集也更适于自动化分析与潜在的格式转换。 本数据集关联了一项研究项目的数据与代码，该项目借助连续字符串转换，将DataONE、环境数据倡议（Environmental Data Initiative）以及美国国家生态观测网（U.S. National Ecological Observatory Network）在2013至2022年间收集的生态元数据中的单位映射至QUDT本体（QUDT ontology）。其中包含的数据实体如下： a) 原始接收状态的元数据（共355,057个单位实例） b) 整合后的原始数据 c) 用于字符串转换的替换表 d) 匹配至QUDT单位的896个不同单位的最终查找表 e) 用于QUDT匹配的关联R代码，以及用于向生态元数据语言（Ecological Metadata Language）元数据文档添加注释元素的Web服务与R函数。 通过上述替换方法与代码，原始元数据中91%的单位实例可成功匹配至QUDT单位。相关数据与研究结果已在论文"Porter JH, M O’Brien, M Frants, S Earl, M Martin, C Laney. (已投稿) 利用单位本体对已有元数据进行注释. 提交至《科学数据》（Scientific Data）"中进行了讨论。