R - Ggplot Line Color (Using Geom_Line) Doesn't Change

R - ggplot line color (using geom_line) doesn't change

Your first code should be

ggplot(data=main_data) +
# black plot
geom_line(aes(x=vectors_growth_rate_with_predator, 
              y=disease_prevalnce_with_predator),
          color = "black") + 
# blue plot
geom_line(aes(x=vectors_growth_rate_with_predator, 
              y=disease_prevalnce_without_predator),
          color = "blue")

You need to put color outside aes().

For your second code you need to reshape your data from wide to long format. You can do this in many ways, the following should work for you.

library(tidyverse)
main_data <- main_data %>% 
               gather(key, value, c("disease_prevalnce_with_predator",
                                    "disease_prevalnce_without_predator")
PrevVSGrowth <- ggplot(data=main_data) +
 geom_line(aes(x=vectors_growth_rate_with_predator, 
               y=value,
               col = key))

PrevVSGrowth + 
scale_color_manual(values = c(disease_prevalnce_with_predator= 'black',
                              disease_prevalnce_without_predator = 'blue'))

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In the first plot we set an aesthetic to a fixed value, in each call to geom_line(). This creates two new variables containing only the value "black" and "blue", respectively. In OP's example the values "black" and "blue" are then scaled to red and lightblue and a legend is added.

In the second plot we map the colour aesthetic to a variable (key in this example). This is usually the preferred way.

ggplot geom_line - setting colour of lines doesn't work?

Try this:

ggplot(myData, aes(x = year, y = value, country = country, colour = I("grey"))) +
geom_line()

R ggplot, set colour for one geom_line but not another

Plot mdt lines with separate geom_line layers and specify colors in them.

For name A plot mean line using: geom_line(data = mdt[name == "A"], col = "#ff5a32") with redish color. For thinner lines specify similar color with scale_color_manual.

library(data.table)
library(ggplot2)

mdt <- dt[, .(value = mean(value)), by = .(name, date)]

ggplot(dt, aes(date, value)) + 
    geom_line(aes(group = type, col = name)) + 
    geom_line(data = mdt[name == "A"], col = "#ff5a32", size = 2) +
    geom_line(data = mdt[name == "B"], col = "#475cd3", size = 2) +
    scale_colour_manual(name = "Name", 
                        values = c("#ff987f", "#8c99e4")) +
    labs(x = "Date",
         y = "Value", 
         title = "Change in value over time") +
    theme_classic()

How to change color (automatically) in geom_line() using R programming language

Try first creating the plot with ggplot2 functions and be careful that fill and color are different things. In order to have a dynamic style you could use ggplotly() from plotly package that allows for some interactive values and customization. Here the code:

library(plotly)
#Code
G1 <- ggplot(data=data_1, aes(x=Month, y=rain, color=factor(Year)))+
  geom_line(stat="identity")+
  theme_minimal()+
  #geom_col(width = 0.05, position = position_dodge(0.7))+
  xlim(0,12)+
  ylim(0,800)+
  xlab("Month")+
  ylab("Rain")+
  ggtitle("Rain according to Month") +
  guides(fill = guide_legend(ncol = 2))
#Dynamic
ggplotly(G1)

Output:

Some data used:

#Data
data_1 <- structure(list(tem = c(16.976, 19.9026, 24.3158, 28.1834, 27.8892, 
28.8925, 28.3327, 27.9243, 27.6057, 27.0887, 16.976, 19.9026, 
24.3158, 28.1834, 27.8892, 28.8925, 28.3327, 27.9243, 27.6057, 
27.0887, 16.976, 19.9026, 24.3158, 28.1834, 27.8892, 28.8925, 
28.3327, 27.9243, 27.6057, 27.0887), Month = c(1L, 2L, 3L, 4L, 
5L, 6L, 7L, 8L, 9L, 10L, 1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L, 
10L, 1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L, 10L), Year = c(1901, 
1901, 1901, 1901, 1901, 1901, 1901, 1901, 1901, 1901, 1902, 1902, 
1902, 1902, 1902, 1902, 1902, 1902, 1902, 1902, 1902, 1902, 1902, 
1902, 1902, 1902, 1902, 1902, 1902, 1902), rain = c(18.5356, 
16.2548, 70.7981, 66.1616, 267.215, 341.042, 540.907, 493.21, 
291.549, 199.171, 18.5356, 16.2548, 70.7981, 66.1616, 267.215, 
341.042, 540.907, 493.21, 291.549, 199.171, 118.5356, 116.2548, 
170.7981, 166.1616, 367.215, 441.042, 640.907, 593.21, 391.549, 
299.171)), row.names = c("1", "2", "3", "4", "5", "6", "7", "8", 
"9", "10", "11", "21", "31", "41", "51", "61", "71", "81", "91", 
"101", "12", "22", "32", "42", "52", "62", "72", "82", "92", 
"102"), class = "data.frame")

Cannot change colors of lines in ggplot

The aes() function is for mapping variables to aesthetic attributes not for changing geoms' properties, you have to specify those outside aes() function, like this:

ggplot(data=SLLN, aes(x=X1, y=X2, group=1)) + 
       geom_line(aes(colour = "Variable name A")) +                    
       geom_hline(aes(yintercept=6, colour = "Variable name B"), linetype="dashed") +
       scale_color_manual(values = c("black","blue")) +
       ... (the rest of your code)

ggplot2 geom_line colors by group but with different colorcodes

You could use the ggnewscale package

library(ggnewscale)

ggplot(df, aes(x = variable1)) +
  geom_line(aes(y = variable2, color = group1)) +
  scale_colour_manual(values = color_group) +
  new_scale_color() +
  geom_line(aes(y = variable3, color = group1)) +
  scale_colour_manual(values = color_flag)

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