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i have the following plot in ggplot2 but I'm not too happy with how the secondary y axis is scaled cause the grey line looks fairly flat.

I would prefer to create a scale for the secondary y axis and the grey line with a range of only 1.75 to 2.25 so that I can see the movements a bit better. Any advice on how to do this?

library(tidyverse)

reserves_level <- structure(list(Date = structure(c(18291, 18321, 18351, 18382, 
18412, 18443, 18473, 18504, 18535, 18565, 18596, 18626, 18657, 
18291, 18321, 18351, 18382, 18412, 18443, 18473, 18504, 18535, 
18565, 18596, 18626, 18657), class = "Date"), Key = c("Reserves (NAD)", 
"Reserves (NAD)", "Reserves (NAD)", "Reserves (NAD)", "Reserves (NAD)", 
"Reserves (NAD)", "Reserves (NAD)", "Reserves (NAD)", "Reserves (NAD)", 
"Reserves (NAD)", "Reserves (NAD)", "Reserves (NAD)", "Reserves (NAD)", 
"Reserves (USD)", "Reserves (USD)", "Reserves (USD)", "Reserves (USD)", 
"Reserves (USD)", "Reserves (USD)", "Reserves (USD)", "Reserves (USD)", 
"Reserves (USD)", "Reserves (USD)", "Reserves (USD)", "Reserves (USD)", 
"Reserves (USD)"), Value = c(30.96107351507, 32.16872169411, 
32.97394333811, 35.6594389906, 32.944455576, 31.75897192528, 
35.3995709836, 33.3870647566, 32.66579275848, 34.35383925875, 
29.92587, 31.7517, 33.35816, 2.06261398712043, 2.05295138288458, 
1.84674175243683, 1.92451004045528, 1.87739090357876, 1.83355302380232, 
2.08125035179437, 1.97135496109494, 1.95207290341642, 2.11488932754343, 
1.94197, 2.10318, 2.20185)), row.names = c(NA, -26L), class = c("tbl_df", 
"tbl", "data.frame"))

ggplot() +
  geom_col(data = subset(reserves_level, Key %in% c("Reserves (NAD)")),
           mapping = aes(x = Date, y = Value, fill = Key),
           position = position_dodge()) +
  geom_line(data = subset(reserves_level, Key == "Reserves (USD)"),
            mapping = aes(x = Date, y = Value*15, group = Key, color = Key),
            size = 2) +
  scale_fill_manual(values = c('#7c3042','#c7af76')) +
  scale_color_manual(values = c('grey')) +
  theme_bw() +
  scale_y_continuous(sec.axis= sec_axis(~./15, name="Reserves (USD)", breaks = seq(0,2.5, by = 0.25)))

enter image description here

Tanga94
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  • Add something like `coord_cartesian(ylim = c(25, 40))`. However, be aware that this type of chart is not recommended: https://blog.datawrapper.de/dualaxis/ – Phil Feb 17 '21 at 03:16
  • This is a highly discussed issue. You should go through this site: . Here you will find your answer. – TarJae Feb 17 '21 at 03:24

1 Answers1

1

May be this can help you

ylim.p <- c(0, 30)   
ylim.s <- c(1.75, 2.25)    

b <- diff(ylim.p)/diff(ylim.s)
a <- b*(ylim.p[1] - ylim.s[1])

ggplot() +
  geom_col(data = subset(reserves_level, Key %in% c("Reserves (NAD)")),
           mapping = aes(x = Date, y = Value, fill = Key),
           position = position_dodge()) +
  geom_line(data = subset(reserves_level, Key == "Reserves (USD)"),
            mapping = aes(x = Date, y = (Value*b)+a, group = Key, color = Key),
            size = 2) +
  scale_fill_manual(values = c('#7c3042','#c7af76')) +
  scale_color_manual(values = c('grey')) +
  theme_bw() +
  scale_y_continuous(sec.axis= sec_axis(~(. - a)/b, name="Reserves (USD)", breaks = seq(1.75,2.5, by = 0.25)))
Jaime Yáñez
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