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根据r中另一列的字符串值创建新列

SNT · 技术社区 · 6 年前

我在r中有一个数据帧,它的列是一个大字符串。我想用这个字符串创建一个具有特定值的新列。

dom <- data.frame(
  Site = c("alpha", "beta", "charlie", "delta"),
  Banner = c("testing_Watermelon -DPI_300x250 v2"   , "notest_Vanilla Latte-DPI_300x250 v2" , "bottle :15s","aaaa vvvv cccc Build_Mobile_320x480")
)

现在如果列标题包含 Watermelon 或 Vanilla label 只应具有值 西瓜 或 香草 其他的 Default . 下面是预期的数据帧应该是什么样子。

grep 或者其他什么有多重病症的东西?

dom_output <- data.frame(
  Site = c("alpha", "beta", "charlie", "delta"),
  Banner = c("testing_Watermelon -bbb_300x250 v2"   , "notest_Orange aaa_300x250 v2"    , "bottle :15s","aaaa vvvv cccc 320x480"),
  label  = c("Watermelon","Vanilla","Default","Default")
)

3 回复 | 直到 5 年前

Gregor Thomas 6 年前

library(stringr)
dom$label = str_extract(dom$Banner, "Watermelon|Vanilla")
dom$label[is.na(dom$label)] <- "Default"
dom
#      Site                              Banner      label
# 1   alpha  testing_Watermelon -DPI_300x250 v2 Watermelon
# 2    beta notest_Vanilla Latte-DPI_300x250 v2    Vanilla
# 3 charlie                         bottle :15s    Default
# 4   delta aaaa vvvv cccc Build_Mobile_320x480    Default

Brigadeiro 6 年前

下面是一个使用基数R的简单解决方案:

#Sample data:
dom <- data.frame(
  Site = c("alpha", "beta", "charlie", "delta"),
  Banner = c("testing_Watermelon -DPI_300x250 v2"   , "notest_Vanilla Latte-DPI_300x250 v2" , "bottle :15s","aaaa vvvv cccc Build_Mobile_320x480")
)


dom$label <- ifelse(grepl("watermelon", dom$Banner, ignore.case = T), "Watermelon",
                    ifelse(grepl("vanilla", dom$Banner, ignore.case = T), "Vanilla", "Default"))

tmfmnk 6 年前

一 base R 可能是:

labels <- paste(c("Watermelon", "Orange"), collapse = "|")

dom$label <- sapply(regmatches(dom$Banner, regexec(labels, dom$Banner)), "[", 1)
dom$label[is.na(dom$label)] <- "Default"

     Site                              Banner      label
1   alpha  testing_Watermelon -DPI_300x250 v2 Watermelon
2    beta  notest_Orange Latte-DPI_300x250 v2     Orange
3 charlie                         bottle :15s    Default
4   delta aaaa vvvv cccc Build_Mobile_320x480    Default

同样的方法也可以用于 dplyr 和 tidyr :

dom %>%
 mutate(label = sapply(regmatches(Banner, regexec(labels, Banner)), "[", 1),
        label = replace_na(label, "Default"))

样本数据:

dom <- data.frame(
 Site = c("alpha", "beta", "charlie", "delta"),
 Banner = c("testing_Watermelon -DPI_300x250 v2"   , "notest_Orange Latte-DPI_300x250 v2" , "bottle :15s","aaaa vvvv cccc Build_Mobile_320x480")
)

M-- 6 年前

library(dplyr)
library(stringi)

dom %>% mutate(label = case_when(stri_detect_fixed(Banner, "Watermelon") ~ "Watermelon",
                                 stri_detect_fixed(Banner, "Vanilla")    ~ "Vanilla",
                                                                   TRUE  ~ "Default"))
#>      Site                              Banner          label
#> 1   alpha  testing_Watermelon -DPI_300x250 v2     Watermelon
#> 2    beta notest_Vanilla Latte-DPI_300x250 v2        Vanilla
#> 3 charlie                         bottle :15s        Default
#> 4   delta aaaa vvvv cccc Build_Mobile_320x480        Default

dom <- data.frame(Site = c("alpha", "beta", "charlie", "delta"),
                  Banner = c("testing_Watermelon -DPI_300x250 v2",
                             "notest_Vanilla Latte-DPI_300x250 v2",
                             "bottle :15s",
                             "aaaa vvvv cccc Build_Mobile_320x480"))