如果我有这样的数据帧结构:
AA1_123.zip
BB2_456.txt
CCC_789.doc
如何将其更改为:
AA1
BB2
CCC
答案 0 :(得分:5)
您可以尝试sub
sub('_.*', '', df1$Col)
#[1] "AA1" "BB2" "CCC"
df1 <- structure(list(Col = c("AA1_123.zip", "BB2_456.txt",
"CCC_789.doc"
)), .Names = "Col", class = "data.frame", row.names = c(NA, -3L))
答案 1 :(得分:1)
如果字符串在开头都是相同的样式,下划线前有三个字符,这将起作用:
df1 <- structure(list(Col = c("AA1_123.zip", "BB2_456.txt",
"CCC_789.doc"
)), .Names = "Col", class = "data.frame", row.names = c(NA, -3L))
> substr(df1$Col, 1, 3)
[1] "AA1" "BB2" "CCC"
答案 2 :(得分:1)
您还可以再次阅读该列,使用comment.char = "_"
清除该行的其余部分。 ÿ
df <- data.frame(x = c("AA1_123.zip", "BB2_456.txt", "CCC_789.doc"))
read.table(text = as.character(df$x), comment.char="_")
# V1
# 1 AA1
# 2 BB2
# 3 CCC
或者您可以使用scan()
scan(text = as.character(df$x), what = "", comment.char="_")
# Read 3 items
# [1] "AA1" "BB2" "CCC"