R ggplot2 x轴未正确显示

Question

My question is in the following.
here is my raw data:

type,com,year,month,value
A,CH,2016,1,0
A,CH,2016,2,0
A,CH,2016,3,0
A,CH,2016,4,0
A,CH,2016,5,0
A,CH,2016,6,0
A,CH,2016,7,0
A,CH,2016,8,0
A,CH,2016,9,453128
A,CH,2016,10,868256
A,CH,2016,11,1015080
A,CH,2016,12,650912
B,CH,2016,1,0
B,CH,2016,2,0
B,CH,2016,3,0
B,CH,2016,4,0
B,CH,2016,5,0
B,CH,2016,6,61273
B,CH,2016,7,27711
B,CH,2016,8,161780
B,CH,2016,9,48889
B,CH,2016,10,72805
B,CH,2016,11,131466
B,CH,2016,12,73756
C,CH,2016,1,0
C,CH,2016,2,0
C,CH,2016,3,0
C,CH,2016,4,0
C,CH,2016,5,0
C,CH,2016,6,0
C,CH,2016,7,0
C,CH,2016,8,2200
C,CH,2016,9,111384
C,CH,2016,10,28758
C,CH,2016,11,21161
C,CH,2016,12,0

I use it to plot a line graph with gglot2 .

The code is:

test <- read.csv("test.csv", header = T)
test_list <- split(test, test$type)
Rplot <- ggplot(test_list$A, aes(x=month, y=value, col=com))+geom_line()
Rplot

My question:
how to let my x-axis to display like month (1,2,3....,12)?
and how can I combine year and month showing on x-axis at the same time.(Jan2016, Feb2016,.....) or (2016/1, 2016/2,.....)

very appreciate.

Answer 1

For the first case, you can convert month to be a factor. The following code would eliminate decimals in the month.

test$month <- as.factor(test$month)
test_list <- split(test, test$type)
Rplot <- ggplot(test_list$A, aes(x=month, y=value, col=com, group = 1))+geom_line()
Rplot

To get numeric months you have to have a new column. I will create a new one using dplyr package and change that.

library(dplyr)
# make a new column by joining month after converting it to character and year.
test <- test %>% mutate(exactDate = paste(month.abb[as.numeric(as.character(month))], year, sep=""))

# convert to factor
test$exactDate <- factor(test$exactDate, levels = c("Jan2016","Feb2016","Mar2016","Apr2016","May2016","Jun2016",
                                                    "Jul2016","Aug2016","Sep2016", "Oct2016", "Nov2016", "Dec2016"),
                         labels =  c("Jan2016","Feb2016","Mar2016","Apr2016","May2016","Jun2016",
                                    "Jul2016","Aug2016","Sep2016", "Oct2016", "Nov2016", "Dec2016"))

# Plot similarly
test_list <- split(test, test$type)
Rplot <- ggplot(test_list$A, aes(x=exactDate, y=value, col=com, group = 1))+geom_line()

# Rotate axis labels by 90 degrees
Rplot+ theme(axis.text.x=element_text(angle=90, hjust=1))

Answer 2

Create date_label column as Date class in the dataframe using ymd() from lubridate package.

library( 'lubridate' )
test_list <- lapply( test_list, function( x ) { 
  x$date_label <- ymd( paste( x$year, month.abb[ x$month ], 01, sep = "-"))
  x 
  })

Manipulate x axis using scale_x_date()

# 1. date_labels = "%Y/%m"   - 2016/01
# 2. date_labels = "%m"      - 01
# 3. date_labels = "%b %Y"   - Jan 2016        

library( 'ggplot2' )
ggplot( data = test_list$A, aes( x = date_label, y = value, color = com, group = com ) ) +
  geom_line( size = 3 ) + 
  scale_x_date(name = "month",
               date_labels = "%m", 
               date_breaks = "1 month" )

ggplot( data = test_list$A, aes( x = date_label, y = value, group = com, color = com ) ) +
  geom_line(  size = 3 ) + 
  theme( axis.text.x = element_text( angle = 45, hjust = 1 )) +
  scale_x_date(name = "month_year",
               date_labels = "%b %Y", 
               date_breaks = "1 month" )