在r中按月/年求和

Question

我从excel电子表格中收到以下格式的历史需求数据：

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

我们可以尝试使用as.yearmon来创建分组变量，然后获取“{1}}的数量＆＃39;在sum

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