在 r 中按月/年求和变量

Question

I receive historical demand data from an excel spreadsheet in the following format:

Part Number  Requested Date       Quantity
123           01/24/2013 12:53       1
122           02/07/2013 09:57       1 
122           02/14/2013 09:58       7
124           11/21/2012 12:46       1

I typically provide my management charts from excel by part like this but I want to be more proficient in R---doing hundreds of these at time

Answer 1

We can try with as.yearmon to create the grouping variable and then get the sum of 'Quantity' in summarise

library(zoo)
library(dplyr)
df1 %>% 
   group_by(PartNumber, yearMon = as.yearmon(RequestedDate, "%m/%d/%Y %H:%M")) %>% 
   summarise(Quantity = sum(Quantity))