Date format

library(readxl)
data <- read_excel("C:/Users/sts-m-06/Desktop/data.xlsx")
head(data)

## # A tibble: 6 x 2
##       date country                                                
##      <dbl> <chr>                                                  
## 1 20180701 Beijing Hongye Hong Food Trade Co.,ltd                 
## 2 20180701 Ulanqab izawa Chang Trading Co.,ltd                    
## 3 20180701 Beijing Hongye Hong Food Trade Co.,ltd                 
## 4 20180701 Beijing Hongye Hong Food Trade Co.,ltd                 
## 5 20180701 Catalpa Erlianhot city Yang Import Export Trade Co.,ltd
## 6 20180701 Hunan Shangdefu Trading Co.,ltd

c=as.Date(as.character(data$date), "%Y%m%d")
date<-c
date<-transform(date)
new_data<-cbind(date,data)
head(new_data)

##       X_data     date
## 1 2018-07-01 20180701
## 2 2018-07-01 20180701
## 3 2018-07-01 20180701
## 4 2018-07-01 20180701
## 5 2018-07-01 20180701
## 6 2018-07-01 20180701
##                                                   country
## 1                  Beijing Hongye Hong Food Trade Co.,ltd
## 2                     Ulanqab izawa Chang Trading Co.,ltd
## 3                  Beijing Hongye Hong Food Trade Co.,ltd
## 4                  Beijing Hongye Hong Food Trade Co.,ltd
## 5 Catalpa Erlianhot city Yang Import Export Trade Co.,ltd
## 6                         Hunan Shangdefu Trading Co.,ltd

write.csv(new_data,file = "new_data.csv")

Date year month merge

library(readxl)
library(zoo)

## 
## Attaching package: 'zoo'

## The following objects are masked from 'package:base':
## 
##     as.Date, as.Date.numeric

data <- read.csv("C:/Users/sts-m-06/Desktop/data.csv")
head(data)

##    JIL SAR
## 1 2017   3
## 2 2017   3
## 3 2017   3
## 4 2017   3
## 5 2017   3
## 6 2017   3

Date <- as.Date(paste(data$JIL, data$SAR, sep="-"), "%Y-%M")
d<-as.yearmon(paste(data$JIL, data$SAR), "%Y%m")
newdata<-cbind(d,data)
head(newdata)

##          d  JIL SAR
## 1 Mar 2017 2017   3
## 2 Mar 2017 2017   3
## 3 Mar 2017 2017   3
## 4 Mar 2017 2017   3
## 5 Mar 2017 2017   3
## 6 Mar 2017 2017   3