Question

我在以下方面遇到了问题：我想将日期格式从“％d％/ m /％y”更改为“％y％/ m /％d”，然后创建一个仅包含YEAR（从列日期中提取年份）。

data$date_of_purchase = as.Date(data$date_of_purchase, "%y%/m/%d")
data$year_of_purchase = as.numeric(format(data$date_of_purchase, "%Y"))

例如：08/01/2019将更改为2008-01-20，但应为2019/01/08。

# Load text file into local variable called 'data'
data = read.delim(file = 'purchases.txt', header = FALSE, sep = '\t', dec = '.')

# Add headers and interpret the last column as a date, extract year of purchase
colnames(data) = c('customer_id', 'purchase_amount', 'date_of_purchase')

#Delete columns with Blank Values
data <- with(data, data[!(customer_id == "" | is.na(customer_id)), ])

data$date_of_purchase = as.Date(data$date_of_purchase, "%y/%m/%d")
data$year_of_purchase = as.numeric(format(data$date_of_purchase, "%Y"))

没有错误消息，但是新日期不是所需的日期。

Answer 1

这是您要寻找的吗？

library("lubridate") ## year comes from this package

Input
data <- fread("customer_id  purchase_amount date_of_purchase
0000@000.com    $22     08/01/2019
0000christie@gmail.com  $174    02/11/2017
0000christie@gmail.com  $61     03/01/2018
000@hotmail.com $33     16/12/2017")

Your code
data$date_of_purchase = as.Date(data$date_of_purchase,"%d/%m/%Y")
data$year_of_purchase <- year(data$date_of_purchase)

OutPut:
              customer_id purchase_amount date_of_purchase year_of_purchase
1:           0000@000.com             $22       2019-01-08             2019
2: 0000christie@gmail.com            $174       2017-11-02             2017
3: 0000christie@gmail.com             $61       2018-01-03             2018
4:        000@hotmail.com             $33       2017-12-16             2017

Answer 2

X $ newdate <-strptime（as.character（X $ date），“％d /％m /％Y”）

format（X $ newdate，“％Y-％m-％d”）

我无法正确格式化所需的输出

2 个答案: