ggplot legend for second axis

Question

I hope you guys can help me. I have a problem creating a graph with ggplot. I want a second y axis that shows the cummulativ rain sum (= kummulative Regenmenge 10 Tage) as points. So far so good. However, the blue points that represent the cummulative rain sum are somehow mixed with the fill for "transtype" in the legend. They should be a seperated element in the legend. I hope you understand what I mean. Thanks a lot in advance. Hope you guys can help me with this issue. :) Here is my data

BF_1189 <- structure(list(Datum = structure(c(18703, 18703, 18703, 18703, 
18703, 18703, 18703, 18703, 18703, 18703, 18724, 18724, 18724, 
18724, 18724, 18724, 18724, 18724, 18724, 18724, 18730, 18730, 
18730, 18730, 18730, 18730, 18730, 18730, 18730, 18730, 18744, 
18744, 18744, 18744, 18744, 18744, 18744, 18744, 18744, 18744, 
18758, 18758, 18758, 18758, 18758, 18758, 18758, 18758, 18758, 
18758, 18774, 18774, 18774, 18774, 18774, 18774, 18774, 18774, 
18774, 18774), class = "Date"), Soll = c("1189", "1189", "1192", 
"1192", "1202", "1202", "2484", "2484", "552", "552", "1189", 
"1189", "1192", "1192", "1202", "1202", "2484", "2484", "552", 
"552", "1189", "1189", "1192", "1192", "1202", "1202", "2484", 
"2484", "552", "552", "1189", "1189", "1192", "1192", "1202", 
"1202", "2484", "2484", "552", "552", "1189", "1189", "1192", 
"1192", "1202", "1202", "2484", "2484", "552", "552", "1189", 
"1189", "1192", "1192", "1202", "1202", "2484", "2484", "552", 
"552"), Transtyp = structure(c(1L, 2L, 1L, 2L, 1L, 2L, 1L, 2L, 
1L, 2L, 1L, 2L, 1L, 2L, 1L, 2L, 1L, 2L, 1L, 2L, 1L, 2L, 1L, 2L, 
1L, 2L, 1L, 2L, 1L, 2L, 1L, 2L, 1L, 2L, 1L, 2L, 1L, 2L, 1L, 2L, 
1L, 2L, 1L, 2L, 1L, 2L, 1L, 2L, 1L, 2L, 1L, 2L, 1L, 2L, 1L, 2L, 
1L, 2L, 1L, 2L), .Label = c("2", "5"), class = "factor"), mittelwert = c(34.015625, 
33.8375, 36.15, 36.6518518518519, 36.975, 36.1193548387097, 33.828125, 
33.3625, 36.1625, 36.5032258064516, 27.109375, 26.775, 28.7625, 
30.128125, 29.590625, 28.50625, 25.7258064516129, 25.340625, 
26.6322580645161, 26.446875, 30.5516129032258, 30.4375, 31.903125, 
32.15625, 32.40625, 30.715625, 28.4875, 29.084375, 28.784375, 
29.9387096774194, 12.15625, 12.26875, 14.6290322580645, 14.6516129032258, 
15.90625, 15.428125, 12.884375, 12.89375, 15.1625, 14.4, 11.9171875, 
14.078125, 13.675, 13.7896551724138, 18.5, 17.071875, 10.578125, 
10.21875, 13.021875, 13.225, 17.065625, 19.83125, 16.2586206896552, 
17.441935483871, 19.75625, 19.15, 15.4451612903226, 14.2741935483871, 
17.641935483871, 17.358064516129), kumsum_1189 = c(36.94, 36.94, 
36.94, 36.94, 36.94, 36.94, 36.94, 36.94, 36.94, 36.94, 21.11, 
21.11, 21.11, 21.11, 21.11, 21.11, 21.11, 21.11, 21.11, 21.11, 
40.56, 40.56, 40.56, 40.56, 40.56, 40.56, 40.56, 40.56, 40.56, 
40.56, 7.76, 7.76, 7.76, 7.76, 7.76, 7.76, 7.76, 7.76, 7.76, 
7.76, 25.04, 25.04, 25.04, 25.04, 25.04, 25.04, 25.04, 25.04, 
25.04, 25.04, 31.86, 31.86, 31.86, 31.86, 31.86, 31.86, 31.86, 
31.86, 31.86, 31.86)), row.names = c(NA, -60L), groups = structure(list(
    Datum = structure(c(18703, 18703, 18703, 18703, 18703, 18724, 
    18724, 18724, 18724, 18724, 18730, 18730, 18730, 18730, 18730, 
    18744, 18744, 18744, 18744, 18744, 18758, 18758, 18758, 18758, 
    18758, 18774, 18774, 18774, 18774, 18774), class = "Date"), 
    Soll = c("1189", "1192", "1202", "2484", "552", "1189", "1192", 
    "1202", "2484", "552", "1189", "1192", "1202", "2484", "552", 
    "1189", "1192", "1202", "2484", "552", "1189", "1192", "1202", 
    "2484", "552", "1189", "1192", "1202", "2484", "552"), .rows = structure(list(
        1:2, 3:4, 5:6, 7:8, 9:10, 11:12, 13:14, 15:16, 17:18, 
        19:20, 21:22, 23:24, 25:26, 27:28, 29:30, 31:32, 33:34, 
        35:36, 37:38, 39:40, 41:42, 43:44, 45:46, 47:48, 49:50, 
        51:52, 53:54, 55:56, 57:58, 59:60), ptype = integer(0), class = c("vctrs_list_of", 
    "vctrs_vctr", "list"))), row.names = c(NA, -30L), class = c("tbl_df", 
"tbl", "data.frame"), .drop = TRUE), class = c("grouped_df", 
"tbl_df", "tbl", "data.frame"))

and here is my code

solle_1189 = c("1189", "1192", "1202", "2484", "552") 
BF_1189 %>% pull(Datum) %>% unique() -> sdates

for(i in solle_1189 ){
        BF_1189 %>% filter (Soll == i) %>%
          group_by(Datum, Soll, Transtyp) %>%
          ggplot(aes(Datum, mittelwert, fill = Transtyp))+
          geom_bar(stat = "Identity", position = "dodge") + 
          geom_point(aes(Datum, kumsum_1189), shape =18, color = "blue", size = 3) +
          scale_y_continuous(name = "Bodenfeuchte in %", sec.axis = sec_axis(~., name = "Kummulative Regenmenge 10 Tage"))+
          scale_x_date(breaks = sdates)+
          theme_minimal()+
          theme(axis.text.x = element_text(angle = 90, vjust = 0.5, hjust=1),
                axis.text = element_text(size = 9),
                axis.title = element_text(size = 10, face = "bold"))+
          scale_fill_grey()+
          labs (title = paste0("Soll ", i)) ->pb
          print(pb)
          #ggsave(paste0("Z:/FOR/FOR-Projects/IPP_Soelle/Daten/Data_Raw/Max_2021/Grafen/Bodenfeuchte_fdr_kumnied_", i, ".png"))
}

Answer 1

You can put col inside aes of geom_point argument:

BF_1189

solle_1189 = c("1189", "1192", "1202", "2484", "552") 
BF_1189 %>% pull(Datum) %>% unique() -> sdates

for(i in solle_1189) {
  BF_1189 %>% filter (Soll == i) %>%
    group_by(Datum, Soll, Transtyp) %>%
    ggplot(aes(Datum, mittelwert, fill = Transtyp)) +
    geom_bar(stat = "Identity", position = "dodge") +
    geom_point(
      aes(Datum, kumsum_1189, color = 'blue'), ## Put color inside aes
      shape = 18,
      size = 3,
      inherit.aes =  FALSE
    ) + 
    scale_color_manual('Cumulative', values = 'blue')+
    scale_y_continuous(name = "Bodenfeuchte in %",
                       sec.axis = sec_axis( ~ ., name = "Kummulative Regenmenge 10 Tage"),) +
    scale_x_date(breaks = sdates) +
    theme_minimal() +
    theme(
      axis.text.x = element_text(
        angle = 90,
        vjust = 0.5,
        hjust = 1
      ),
      axis.text = element_text(size = 9),
      axis.title = element_text(size = 10, face = "bold")
    ) +
    scale_fill_grey() +
    labs (title = paste0("Soll ", i)) -> pb
  print(pb)
  #ggsave(paste0("Z:/FOR/FOR-Projects/IPP_Soelle/Daten/Data_Raw/Max_2021/Grafen/Bodenfeuchte_fdr_kumnied_", i, ".png"))
}

Answer 2

One potential solution to your problem is to create a new variable (e.g. "Regen") via mutate() and map an aesthetic to it, e.g.

BF_1189 <- BF_1189 %>% 
  mutate(Regen = "Kummulative")

for (i in solle_1189) {
  BF_1189 %>% filter (Soll == i) %>%
    group_by(Datum, Soll, Transtyp) %>%
    ggplot(aes(x = Datum, y = mittelwert))+
    geom_bar(aes(fill = Transtyp), stat = "Identity",
             position = "dodge") + 
    geom_point(aes(y = kumsum_1189, size = Regen),
               shape = 18, color = "blue") +
    scale_y_continuous(name = "Bodenfeuchte in %",
                       sec.axis = sec_axis(~., name = "Kummulative Regenmenge 10 Tage")) +
    scale_x_date(breaks = sdates)+
    theme_minimal()+
    theme(axis.text.x = element_text(angle = 90, vjust = 0.5, hjust=1),
          axis.text = element_text(size = 9),
          axis.title = element_text(size = 10, face = "bold")) +
    scale_fill_grey() +
    labs (title = paste0("Soll ", i)) -> pb
  print(pb)
  #ggsave(paste0("Z:/FOR/FOR-Projects/IPP_Soelle/Daten/Data_Raw/Max_2021/Grafen/Bodenfeuchte_fdr_kumnied_", i, ".png"))
}

Does that solve your problem?