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执行如下代码,原本的意愿是从压缩文件中读取大个头的文本文件,考虑到RAM一次只读取一条,保留感兴趣的内容以便后继计算,但是执行nextElem()后只能返回第一行,和直接从文本文件返回的ireadLines是有区别的,这是为什么呢?或者有没有其它方法或库作为顶替的解决方案?
- > library(iterators)
- > con<-unz(description='daily_VOCS_1994.zip',filename='daily_VOCS_1994.csv')
- > it<-ireadLines(con)
- > nextElem(it)
- [1] "\"State Code\",\"County Code\",\"Site Num\",\"Parameter Code\",\"POC\",\"Latitude\",\"Longitude\",\"Datum\",\"Parameter Name\",\"Sample Duration\",\"Pollutant Standard\",\"Date Local\",\"Units of Measure\",\"Event Type\",\"Observation Count\",\"Observation Percent\",\"Arithmetic Mean\",\"1st Max Value\",\"1st Max Hour\",\"AQI\",\"Method Name\",\"Local Site Name\",\"Address\",\"State Name\",\"County Name\",\"City Name\",\"CBSA Name\",\"Date of Last Change\""
- > nextElem(it)
- [1] "\"State Code\",\"County Code\",\"Site Num\",\"Parameter Code\",\"POC\",\"Latitude\",\"Longitude\",\"Datum\",\"Parameter Name\",\"Sample Duration\",\"Pollutant Standard\",\"Date Local\",\"Units of Measure\",\"Event Type\",\"Observation Count\",\"Observation Percent\",\"Arithmetic Mean\",\"1st Max Value\",\"1st Max Hour\",\"AQI\",\"Method Name\",\"Local Site Name\",\"Address\",\"State Name\",\"County Name\",\"City Name\",\"CBSA Name\",\"Date of Last Change\""
- >
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