Question

如果列名中的最后几个字符符合某个条件，或者从一开始就调整当前代码，我需要帮助才能删除它们。

我正在处理有关Common Core评估的学生测试数据，而且列名不遵循一致的格式。数据框的结构如下：

>name(df)
[1] Student.ID
[2] State.ID
[3] A1_2.MD.A.1
[4] A1_2.MD.A.3
[5] A1_2.MD.A.4
[6] A1_2.MD.B.5
[7] A1_2.NBT.A.1
[8] A1_2.NBT.A.1.a
[9] A1_2.NBT.A.1.b
[10] A1_2.NBT.A.3

这是我想要的结果：

library(reshape2)
library(reshape)
library(stringr)
library(dplyr)
library(qdap)

for (column in c(3:ncol(df))) {
  colnames(df)[column] <- substr(colnames(df[column],4,nchar(colnames(df)[column]))
}

## reduce column names to only the letter and number (strip the description)
for (column in c(3:ncol(df))) {
if (nchar(beg2char(colnames(df)[column],".")) < 3) {
  colnames(df)[column] <- substr(colnames(df[column],1,8)
  } else if (nchar(beg2char(colnames(df)[column],".")) > 2){
  colnames(df)[column] <- substr(colnames(df)[column],1,9)
  }
}
## add screening number indicator to start of percent scores
for (column in c(3:ncol(df))) {
  colnames(df)[column] <- paste("A1_2", colnames(df)[column], sep=".")
}

这是我到目前为止的代码，但它只是让我的一部分：

>name(df)
[1] Student.ID
[2] State.ID
[3] A1_2.MD.A.1.S
[4] A1_2.MD.A.3.E
[5] A1_2.MD.A.4.M
[6] A1_2.MD.B.5.A
[7] A1_2.NBT.A.1.U
[8] A1_2.NBT.A.1.a
[9] A1_2.NBT.A.1.b
[10] A1_2.NBT.A.3.R

现在我得到了：

{{1}}

提前感谢您的帮助！

Answer 1

您可以使用

names <- c(your_col_names_here)
names <- gsub("^X2\\.((?:[^.]+\\.){2}[^.]+(?:\\.[a-z])?).*",
              "A1_2.\\1", names)
names(df) <- names

见a demo on regex101.com。

<小时/> 整个R代码段：

# create a dummy df to test with
df <- as.data.frame(matrix(0, ncol = 10, nrow = 1))
names <- c("Student.ID", "State.ID",
           "X2.MD.A.1.Select.and.Use.Appropriate.Tools.to.Measure.Length.Percent.Correct",
           "X2.MD.A.3.Estimate.Length.Percent.Correct",
           "X2.MD.A.4.Measurement.Difference.Percent.Correct",
           "X2.MD.B.5.Addition.and.Subtraction.Word.Problems..Lengths.Percent.Correct",
           "X2.NBT.A.1.Understand.Place.Value.Percent.Correct",
           "X2.NBT.A.1.a.Understand.Place.Value..Bundles.of.Tens.Percent.Correct",
           "X2.NBT.A.1.b.Understand.Place.Value..Bundles.of.Hundreds.Percent.Correct",
           "X2.NBT.A.3.Read.and.Write.Numbers.to.1.000.Percent.Correct")

names(df) <- gsub(pattern = "^X2\\.((?:[^.]+\\.){2}[^.]+(?:\\.[a-z])?).*", "A1_2.\\1", names)
df

从R中的列名中删除特定的最后一个字符

1 个答案: