如何将数据框中的年份值转换为两位数的值？

Question

我尝试使用此公式将数据框“年”中提到的年份转换为2位数字的值

yr <- format((Yr[,]), format = "%y")

注意：Yr是一个由年份值viz组成的data.frame。 2015、2012、1998等。我尝试将这些值分别以以下格式15、12、98加载到变量yr中。

Answer 1

sprintf("%02d", Year %% 100)怎么样？

Year <- 1960:2016
sprintf("%02d", Year %% 100)
# [1] "60" "61" "62" "63" "64" "65" "66" "67" "68" "69" "70" "71" "72" "73" "74"
#[16] "75" "76" "77" "78" "79" "80" "81" "82" "83" "84" "85" "86" "87" "88" "89"
#[31] "90" "91" "92" "93" "94" "95" "96" "97" "98" "99" "00" "01" "02" "03" "04"
#[46] "05" "06" "07" "08" "09" "10" "11" "12" "13" "14" "15" "16"

另一种方法是使用substr ，如@alistaire所述：

substr(Year, 3, 4)
# [1] "60" "61" "62" "63" "64" "65" "66" "67" "68" "69" "70" "71" "72" "73" "74"
#[16] "75" "76" "77" "78" "79" "80" "81" "82" "83" "84" "85" "86" "87" "88" "89"
#[31] "90" "91" "92" "93" "94" "95" "96" "97" "98" "99" "00" "01" "02" "03" "04"
#[46] "05" "06" "07" "08" "09" "10" "11" "12" "13" "14" "15" "16"