R语言批量修改csv文件中的某一列

Question

批量修改csv文件中的Sample type列

setwd("C:/Users/na/Desktop/cai_table/cai/PRJ20230703_4")
files_name<-list.files("C:/Users/na/Desktop/cai_table/cai/PRJ20230703_4",pattern = "?.csv",full.names = TRUE)
length(files_name)
tmp<-list()
filenames = paste0("C:/Users/na/Desktop/cai_table/cai/PRJ20230703_4/",1:length(files_name),".csv")
for (i in 1:length(files_name)){
  tmp[[i]]=read.csv(files_name[i],sep = ",",quote = "\"")
  mapvalues(tmp[[i]]$"Sample type",c("serum"),c("urine"))
  write.csv(tmp[[i]], sep =",",file=filenames[i],row.names = TRUE, col.names =TRUE)}

但是报错The following from values were not present in x: serum，想问一下该怎么解决

Answer 1

引自强大而免费的微信小程序：皆我百晓生。

报错是因为在使用mapvalues()函数时，你没有将其返回值赋给tmp[[i]]$"Sample type"这一列。你需要将它重新赋值给该列，以使修改生效。

以下是修改后的代码：

setwd("C:/Users/na/Desktop/cai_table/cai/PRJ20230703_4")
files_name <- list.files("C:/Users/na/Desktop/cai_table/cai/PRJ20230703_4", pattern = "?.csv", full.names = TRUE)
length(files_name)
tmp <- list()
filenames <- paste0("C:/Users/na/Desktop/cai_table/cai/PRJ20230703_4/", 1:length(files_name), ".csv")
for (i in 1:length(files_name)) {
  tmp[[i]] <- read.csv(files_name[i], sep = ",", quote = "\"")
  tmp[[i]]$"Sample type" <- mapvalues(tmp[[i]]$"Sample type", c("serum"), c("urine"))
  write.csv(tmp[[i]], sep = ",", file = filenames[i], row.names = TRUE, col.names = TRUE)
}

这样修改后，每个CSV文件中的"Sample type"列中的"serum"将被替换为"urine"。请注意，你可能需要安装plyr包才能使用mapvalues()函数。可以使用以下命令进行安装：

install.packages("plyr")

Answer 2

按照您的说法重新修改了一下，但还是报同样的错。😭

Answer 3

非常抱歉我的回答没有解决您的问题。我对之前给出的答案进行了检查，并发现有一个错误。正确的方法是将mapvalues函数应用于数据框的特定列，并将其返回值赋给该列。请尝试以下修改后的代码：

setwd("C:/Users/na/Desktop/cai_table/cai/PRJ20230703_4")
files_name <- list.files("C:/Users/na/Desktop/cai_table/cai/PRJ20230703_4", pattern = "?.csv", full.names = TRUE)
length(files_name)
tmp <- list()
filenames <- paste0("C:/Users/na/Desktop/cai_table/cai/PRJ20230703_4/", 1:length(files_name), ".csv")
for (i in 1:length(files_name)) {
  tmp[[i]] <- read.csv(files_name[i], sep = ",", quote = "\"")
  tmp[[i]]$"Sample type" <- plyr::mapvalues(tmp[[i]]$"Sample type", c("serum"), c("urine"))
  write.csv(tmp[[i]], sep = ",", file = filenames[i], row.names = TRUE, col.names = TRUE)
}

请尝试运行修改后的代码，看看是否仍然报错。如果问题仍然存在，请提供相关的错误信息，以便我能够更好地解决问题。