[R] R: Drawing a vertical line

[Gregory Coats]

I understand how to use grid to draw chocolate colored dashed horizontal lines.
I understand how to use abline to draw a solid red horizontal line.
I do not understand why using abline, R refuses to draw a solid vertical green line.
grid  (nx = NA, ny = NULL, lty=4, lwd=1, col="chocolate")
abline(h=1750, col="red")
abline(v=2020, col="green”) 
Greg Coats
dta <- read.table( text =
"Year Mon Day Cost kwhr kwhr2 Days text
 2016  5 16  97.89   786 kwhr  29 days
 2016  6 15 120.67   969 kwhr  32 days
 2016  7 15 132.89  1087 kwhr  30 days
 2016  8 15 146.51  1215 kwhr  29 days
 2016  9 14 149.88  1241 kwhr  32 days
 2016 10 13  91.12   737 kwhr  29 days
 2016 11 14  95.23   775 kwhr  29 days
 2016 12 14 142.34  1292 kwhr  33 days
 2017  1 17 162.85  1519 kwhr  31 days
 2017  2 15 150.71  1385 kwhr  32 days
 2017  3 16 132.75  1186 kwhr  29 days
 2017  4 17 112.22   951 kwhr  29 days
 2017  5 16  90.62   722 kwhr  32 days
 2017  6 15 101.26   817 kwhr  30 days
 2017  7 17 125.55  1004 kwhr  30 days
 2017  8 15 124.38   978 kwhr  31 days
 2017  9 14  97.22   762 kwhr  30 days
 2017 10 13  87.52   683 kwhr  29 days
 2017 11 14  99.64   791 kwhr  32 days
 2017 12 14 137.18  1190 kwhr  30 days
 2018  1 16 221.46  2086 kwhr  30 days
 2018  2 14 285.58  2763 kwhr  32 days
 2018  3 15 144.84  1266 kwhr  28 days
 2018  4 16 148.56  1314 kwhr  31 days
 2018  5 15 102.17   826 kwhr  31 days
 2018  6 14 113.60   914 kwhr  30 days
 2018  7 16 125.16  1217 kwhr  30 days
 2018  8 14 160.51  1295 kwhr  31 days
 2018  9 13 131.77  1060 kwhr  30 days
 2018 10 12 103.72   840 kwhr  29 days
 2018 11 13  97.15   776 kwhr  29 days
 2018 12 13 177.43  1628 kwhr  33 days
 2019  1 15 162.35  1623 kwhr  33 days
 2019  2 14 279.97  2649 kwhr  30 days
 2019  3 15 223.43  2046 kwhr  29 days
 2019  4 15 104.24   821 kwhr  29 days
 2019  5 15  82.61   632 kwhr  32 days
 2019  6 14  63.28   836 kwhr  30 days
 2019  7 16 127.36  1018 kwhr  32 days
 2019  8 14 126.32  1024 kwhr  29 days
 2019  9 13 111.41   880 kwhr  30 days
 2019 10 14  88.60   662 kwhr  29 days
 2019 11 13 104.08   788 kwhr  32 days
 2019 12 19 143.04  1157 kwhr  30 days
 2020  1 23 169.55  1417 kwhr  33 days
 2020  2 24 151.28  1242 kwhr  30 days
 2020  3 24 135.98  1095 kwhr  29 days
 2020  4 23 110.43   845 kwhr  32 days
 2020  5 22 100.65   774 kwhr  29 days
 2020  6 23  91.92   718 kwhr  30 days
 2020  7 23 123.30   977 kwhr  32 days
 2020  8 21 131.87  1048 kwhr  29 days
 2020  9 22 109.86   869 kwhr  30 days
 2020 10 20  83.86   644 kwhr  31 days
 2020 11 20  92.57   721 kwhr  29 days
 2020 12 22 143.78  1241 kwhr  32 days
 2021  1 22 197.93  1805 kwhr  32 days
 2021  2 23 211.95  1952 kwhr  30 days
 2021  3 24 194.58  1771 kwhr  31 days
 2021  4 23 118.43   974 kwhr  30 days
 2021  5 24  89.88   694 kwhr  29 days
 2021  6 23 101.75   796 kwhr  32 days
 2021  7 23 103.03   795 kwhr  30 days
 2021  8 23  99.95   756 kwhr  29 days
 2021  9 20 102.70   788 kwhr  32 days
 2021 10 20  74.57   558 kwhr  29 days
 2021 11 22 110.08   881 kwhr  29 days
 2021 12 22 181.03  1597 kwhr  29 days
 2022  1 13 160.41  1513 kwhr  30 days
 2022  2 14 253.07  2352 kwhr  30 days
 2022  3 15 136.15  1202 kwhr  31 days
 2022  4 13  98.33   829 kwhr  29 days
 2022  5 13  78.96   658 kwhr  30 days
 2022  6 14  76.76   633 kwhr  32 days
", header=TRUE )
dta$Dtm <- with( dta, as.Date( ISOdate(Year, Mon, Day ) ) )
with  (dta, plot( Dtm, kwhr, type="l", xlab="Years", ylab="kwhr" ))
grid  (nx = NA, ny = NULL, lty=4, lwd=1, col="chocolate")
abline(h=1750, col="red")
abline(v=2020, col="green") 


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