各位堆栈溢出专家,
我正在尝试使用sqldf删除r表中的行,如下所示:
structure(list(Similarity = c(999L, 888L, 756L, 879L, 567L, 567L), Peak = c(797L, 833L,999L, 798L, 834L, 444L), Formula = structure(c(4L,3L, 4L, 1L, 2L, 2L), .Label = c("C12H26S", "C16H19NO", "C2H8O2Si","C9H13NO2"), class = "factor")), .Names = c("Similarity", "Peak","Formula"), class = "data.frame", row.names = c(NA, -6L))
我的目标是删除公式列中出现"SI“的行,如下所示:
structure(list(Similarity = c(999L, 756L, 879L, 567L, 567L),
Peak = c(797L, 999L, 798L, 834L, 444L), Formula = structure(c(3L,
3L, 1L, 2L, 2L), .Label = c("C12H26S", "C16H19NO", "C9H13NO2"
), class = "factor")), .Names = c("Similarity", "Peak", "Formula"
), class = "data.frame", row.names = c(NA, -5L))
我尝试过sqldf语句:
sqldf("DELETE * FROM PO_raw WHERE Formula='Si'")
但是,当然,它不起作用,因为没有只有"Si“的行。我是sqldf的初学者,在我看来这可能是语法上的错误。我已经在网上搜索过了,但没有找到任何例子。
有什么建议吗?使用sqldf可以做到这一点吗?
干杯,
弗朗西斯科
发布于 2012-12-10 23:19:56
使用LIKE和通配符,如下所示:
> sqldf(c("DELETE FROM PO_raw WHERE Formula like '%Si'", "select * from main.PO_raw"))
Similarity Peak Formula
1 999 797 C9H13NO2
2 756 999 C9H13NO2
3 879 798 C12H26S
4 567 834 C16H19NO
5 567 444 C16H19NO
(顺便说一句:有趣的question about LIKE)
https://stackoverflow.com/questions/13803718
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