Question

我实现了两个函数reshape_long和reshape_wide（请参阅下面的完整工作示例）来重塑数据框架。我创建了几个小例子，这两个函数似乎正常工作。

但是，使用reshape_wide功能在我的真实数据集（大约200.000到300.000行）失败。发生的事情是将X，Y和Z的所有值都设置为1。我的实际数据结构与下面的小例子完全相同。在工作了2天后，我想到了问题是“主键”（test_name，group_name和id）仅在广泛形式中是唯一的。申请后 reshape_long功能主键不再是唯一的。我在想，有谁能告诉我是否有一步由于d1 -> reshape_wide -> d2的非唯一性，d1可以发挥作用吗？

library(reshape2) 
library(taRifx) 

reshape_long <- function(data, ids) {      
        # Bring data into long form 
        data_long <- melt(data, id.vars = ids, 
                          variable.name="Data_Points", value.name="value") 
        data_long$value <- as.numeric(data_long$value) 
        # Remove rows were analyte value is NA 
        data_long <- data_long[!is.na(data_long$value), ] 
        # Resort data 
        formula_sort <- as.formula(paste("~", paste(ids, collapse="+"))) 
        data_long <- sort(data_long, f = formula_sort) 
        return(data_long) 
} 

reshape_wide <- function(data, ids) { 
        # Bring data into wide form 
        formula_wide <- as.formula(paste(paste(ids, collapse="+"), 
                                   "~ Data_Points")) 
        data_wide <- dcast(data, formula_wide) 
        # Resort data 
        formula_sort <- as.formula(paste("~", paste(ids, collapse="+"))) 
        data_wide <- sort(data_wide, f = formula_sort) 
        return(data_wide) 
} 

d <- data.frame( 
        test_name = c(rep("Test_A", 6), rep("Test_B", 6)), 
        group_name = c(rep("Group_C", 3), rep("Group_D", 3), 
                       rep("Group_C", 3), rep("Group_D", 3)), 
        id = c("I1", "I2", "I3", "I4", "I5", "I6",                           
               "I1", "I2", "I3", "I7", "I8", "I9"), 
        X = c(NA,NA,1,2,3,4,5,6,NA,7,8,9), 
        Y = as.numeric(10:21), 
        Z = c(NA,22,23,NA,24,NA,25,26,NA,27,28,29) 
) 

d 
d1 <- reshape_long(d, ids=c("test_name", "group_name", "id")) 
d1 
d2 <- reshape_wide(d1, ids=c("test_name", "group_name", "id")) 
d2 

identical(d,d2)

Answer 1

您编写函数的方式，假设您的示例中ids（test_name，group_name和id的组合在原始数据。最简单的方法是获取d和重复的行。

> ddup <- rbind(d,d)
> ddup1 <- reshape_long(ddup, ids=c("test_name", "group_name", "id")) 
> ddup2 <- reshape_wide(ddup1, ids=c("test_name", "group_name", "id")) 
Aggregation function missing: defaulting to length
> 
> identical(ddup,ddup2) 
[1] FALSE

请注意，您的reshape_wide会认为ids和Data_Points是唯一的。在这个例子中，它们不是。警告消息表明dcast已使用length将每个组合的多个值汇总为单个值。

用dcast重塑数据框并融化

1 个答案: