How to plot missing dates in time series data using ggplot2?

I have a time series data of Temperature (average, maximum, minimum) with missing dates, and the line plot is not continue, this graph does a jump with a horizontal line until the next date. I would like that the line be continue.

My data set is the next

Fecha      -- T      Tmin Tmax

1. Fecha      ---------- T   --   Tmin Tmax
2. 2015-07-01   - 11,16 - 7,3 -  17 
3. 2015-07-02    - 11,49 -   8   - 17,1
4. 2015-07-03   - 11,2 -    8,8 -     15,8
5. 2015-07-04 - 11,20 - 8,6  - 16
6. 2015-07-05    -11,23 -   8,9  - 15,7
7. 2015-07-06    -10,40  - 7,7  -  15,4
8. 2015-07-07 - 10,10 - 8,1 -  14,8
9. 2015-07-08 - 10,04 - 7,3 -  15,4
10. 2018-01-01   - 11,08 -  4,9 -  17,8
11. 2018-01-02   -11,40 -   4,2 -  16,3
12. 2018-01-03 -    9,000 - 5,5  - 13,5
13. 2018-01-04  - 8,584  - 6    -  12,8
14. 2018-01-05  - 8,679  - 7,3  -  11,9
15. 2018-01-06 -    8,75 -  6,8 -  13
16. 2018-01-07   - 9,33 - 6,4    - 15,2
17. 2018-01-08  - 9,63 -    6,3 -  13,9

My code is:

setwd("C:/Users/2018/Documents/Belmira")
dir()
mmp1<-read.csv2("Temperatura.csv")
head(mmp1)
p<-as.Date(mmp1$Fecha)
mmp1$Fecha<-p
w<-ggplot() +
  geom_line(mapping = aes(x = mmp1$Fecha, y = mmp1$Tmin, colour="Min"), size=0.71) +
  geom_line(mapping = aes(x = mmp1$Fecha, y = mmp1$T, colour="P"), size=0.71) +
  geom_line(mapping = aes(x = mmp1$Fecha, y = mmp1$Tmax, colour="Max"), size=0.71) +
  ylim(c(1,18))+
  theme (text = element_text(size=11)) +
  ylab(expression("Temperatura (°C)"))+
  xlab(expression("Tiempo"))+
  scale_x_date(labels = date_format("%d/%m"))+
  theme(axis.text.x=element_text(angle=45, hjust=1))+
  scale_x_date(date_breaks = "30 day", date_labels = "%m-%y", limits = as.Date(c('2015-07-01','2019-01-01')), expand = (c(0.001,0.008)))+
  theme(plot.title = element_text(hjust = 0.5))+
  theme(panel.background = element_rect(fill = 'white', colour = 'white', size = 1.2, linetype = 7))+
  theme(text=element_text(family="arial", face="bold", size=12))+
  theme(axis.title.y = element_text(face="bold", family = "arial", vjust=1.5, colour="black", hjust = 0.5, size=rel(1.2)))+
  theme(axis.title.x = element_text(face="bold", family = "arial", vjust=0.5, colour="black", size=rel(1.2)))+
  theme(axis.text.x = element_text(family= "arial",face = "plain", colour="black", size=rel(1.1)))+
  theme(axis.text.y = element_text(family= "arial",face = "plain", colour="black", size=rel(1.1)))+
  theme(axis.line = element_line(size = 1, colour = "black"))+
  scale_y_continuous(breaks=seq(-4, 28, 2), limits = c(-4,28), expand=c(0,0))+
  scale_colour_manual(name="Leyenda",
                      values=c(Min="green", P="#56B4E9", Max="Red"))+
  theme(legend.title = element_text(colour="black", size=12, face="bold", family = "arial"))+
  theme(legend.key = element_rect(fill = "white"))+
  guides(colour=guide_legend(order = 2),
         shape=guide_legend(order = 2))
w

the result is:

Solution

If I got you right you want the gaps in your data not show up as "a long horizontal" line? This is no simple task. Perhaps the prefered and simplest solution would be to use facetting, e.g. by year. If you insist on having all the data in one plot then you have to try a hacky approach, by getting rid of the date-axis and setting the labels manually. Have a look at the different approaches:

df <- read.table(text="
    Fecha - T - Tmin - Tmax
    2015-07-01 - 11,16 - 7,3 - 17
    2015-07-02 - 11,49 - 8 - 17,1
    2015-07-03 - 11,2 - 8,8 - 15,8
    2015-07-04 - 11,20 - 8,6 - 16
    2015-07-05 - 11,23 - 8,9 - 15,7
    2015-07-06 - 10,40 - 7,7 - 15,4
    2015-07-07 - 10,10 - 8,1 - 14,8
    2015-07-08 - 10,04 - 7,3 - 15,4
    2018-01-01 - 11,08 - 4,9 - 17,8
    2018-01-02 - 11,40 - 4,2 - 16,3
    2018-01-03 - 9,000 - 5,5 - 13,5
    2018-01-04 - 8,584 - 6 - 12,8
    2018-01-05 - 8,679 - 7,3 - 11,9
    2018-01-06 - 8,75 - 6,8 - 13
    2018-01-07 - 9,33 - 6,4 - 15,2
    2018-01-08 - 9,63 - 6,3 - 13,9
", header = TRUE, dec = ",")

mmp1 <- df[,!grepl("^X", names(df))]
mmp1$Fecha <- as.Date(mmp1$Fecha)

library(ggplot2)
library(scales)
library(dplyr)
library(tibble)

mmp2 <- mmp1 %>% 
  mutate(
    year_fecha = as.character(lubridate::year(Fecha)),
    Fecha2 = format(Fecha, "%d-%m"),
    Fecha2 = forcats::fct_reorder(Fecha2, Fecha)) %>% 
  arrange(Fecha) %>% 
  rowid_to_column(var = "Fecha3")

# Put the theme code aside
polish <- theme(text = element_text(size=11)) +
  theme(axis.text.x=element_text(angle=45, hjust=1))+
  theme(plot.title = element_text(hjust = 0.5))+
  theme(panel.background = element_rect(fill = 'white', colour = 'white', size = 1.2, linetype = 7))+
  theme(text=element_text(family="arial", face="bold", size=12))+
  theme(axis.title.y = element_text(face="bold", family = "arial", vjust=1.5, colour="black", hjust = 0.5, size=rel(1.2)))+
  theme(axis.title.x = element_text(face="bold", family = "arial", vjust=0.5, colour="black", size=rel(1.2)))+
  theme(axis.text.x = element_text(family= "sans",face = "plain", colour="black", size=rel(1.1)))+
  theme(axis.text.y = element_text(family= "sans",face = "plain", colour="black", size=rel(1.1)))+
  theme(axis.line = element_line(size = 1, colour = "black"))+
  theme(legend.title = element_text(colour="black", size=12, face="bold", family = "arial"))+
  theme(legend.key = element_rect(fill = "white"))

# Simple and prefered solution: Facet by e.g. by year
w1 <- ggplot(data = mmp2) +
  geom_line(mapping = aes(x = Fecha, y = Tmin, colour="Min"), size=0.71) +
  geom_line(mapping = aes(x = Fecha, y = T, colour="P"), size=0.71) +
  geom_line(mapping = aes(x = Fecha, y = Tmax, colour="Max"), size=0.71) +
  scale_x_date(date_breaks = "1 day", date_labels = "%d-%m", expand = (c(0.001,0.008)))+
  scale_y_continuous(breaks=seq(-4, 28, 2), limits = c(1,18), expand=c(0,0)) +
  scale_colour_manual(name="Leyenda",
                      values=c(Min="green", P="#56B4E9", Max="Red")) +
  ylab("Temperatura (C)")+
  xlab("Tiempo") +
  guides(colour=guide_legend(order = 2),
         shape=guide_legend(order = 2)) +
  facet_wrap(~year_fecha, scales = "free_x") +
  polish

w1

# Hacky solutions with some manual labelling
labs <- select(mmp2, Fecha3, Fecha2) %>% 
  tibble::deframe()

date_lab <- function(x) {
  labs[as.character(x)]
}

# Draw the data as one continuous line
w2 <- ggplot(data = mmp2) +
  geom_line(mapping = aes(x = Fecha3, y = Tmin, colour="Min"), size=0.71) +
  geom_line(mapping = aes(x = Fecha3, y = T, colour="P"), size=0.71) +
  geom_line(mapping = aes(x = Fecha3, y = Tmax, colour="Max"), size=0.71) +
  scale_x_continuous(breaks = as.integer(names(labs)), labels = date_lab, expand = (c(0.001,0.008))) +
  scale_y_continuous(breaks=seq(-4, 28, 2), limits = c(1,18), expand=c(0,0)) +
  scale_colour_manual(name="Leyenda",
                      values=c(Min="green", P="#56B4E9", Max="Red")) +
  ylab("Temperatura (C)")+
  xlab("Tiempo") +
  guides(colour=guide_legend(order = 2),
         shape=guide_legend(order = 2)) +
  polish
w2

# Separate lines for years by using different linetypes 
w3 <- ggplot(data = mmp2) +
  geom_line(mapping = aes(x = Fecha3, y = Tmin, colour="Min", linetype = year_fecha), size=0.71) +
  geom_line(mapping = aes(x = Fecha3, y = T, colour="P", linetype = year_fecha), size=0.71) +
  geom_line(mapping = aes(x = Fecha3, y = Tmax, colour="Max", linetype = year_fecha), size=0.71) +
  scale_x_continuous(breaks = as.integer(names(labs)), labels = date_lab, expand = (c(0.001,0.008))) +
  scale_y_continuous(breaks=seq(-4, 28, 2), limits = c(1,18), expand=c(0,0)) +
  scale_colour_manual(name="Leyenda",
                      values=c(Min="green", P="#56B4E9", Max="Red")) +
  ylab("Temperatura (C)")+
  xlab("Tiempo") +
  guides(colour=guide_legend(order = 2),
         shape=guide_legend(order = 2)) +
  polish
w3

^{Created on 2020-03-28 by the reprex package (v0.3.0)}