索引數據幀

Question

我有一個包含 幾百日期的日期格式例如一列的數據幀：

as.Date(c("2011-08-13","2011-09-13","2010-06-12","2012-09-13","2010-09-13","2012-05-26","2012-07-20")) 

現在，我想只選擇行，其中15.03 <日期< 15.8 （3月15日至10月15日之間的所有日期，無視當年）。有沒有簡單的方法來選擇（索引）在這樣的 方式？

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我稍微修改我接受了答案，如下：

a <- as.Date(c("2011-08-13","2011-09-13","2010-06-12","2012-09-13","2010-09-13","2012-05-26","2012-07-20")) 
lower <- as.Date("03-15",format="%m-%d") 
upper <- as.Date("08-15",format="%m-%d") 
a[format(a,"%m-%d") < format(upper,"%m-%d") & format(a,"%m-%d") > format(lower,"%m-%d")] 
[1] "2011-08-13" "2010-06-12" "2012-05-26" "2012-07-20" 

Answer 1

在base，這個想法是使用功能format：

a <- as.Date(c("2011-08-13","2011-09-13","2010-06-12","2012-09-13","2010-09-13","2012-05-26","2012-07-20")) 
lower <- as.Date("2012-03-15") 
upper <- as.Date("2012-08-15") 
a[format(a,"%m-%d") < format(upper,"%m-%d") & format(a,"%m-%d") > format(lower,"%m-%d")] 
[1] "2011-08-13" "2010-06-12" "2012-05-26" "2012-07-20"