R-当don'；我不知道行号

如果有data.frame名称'DF'，我不知道行号时如何输入'yellow'，谢谢

从

到

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一种方法是创建一个查找数据框，然后根据

结果
匹配

color_fruit <- data.frame(fruit = c('apple', 'banana', 'orange'), 
              color = c('red', 'yellow', 'orange'), stringsAsFactors = FALSE)

df$color <- color_fruit$color[match(df$fruit, color_fruit$fruit)]
df

#   fruit year  color
#1  apple 2017    red
#2  apple 2018    red
#3  apple 2019    red
#4 banana 2017 yellow
#5 banana 2018 yellow
#6 banana 2019 yellow
#7 orange 2017 orange
#8 orange 2018 orange
#9 orange 2019 orange

数据

df <- structure(list(fruit = c("apple", "apple", "apple", "banana", 
"banana", "banana", "orange", "orange", "orange"), year = c(2017L, 
2018L, 2019L, 2017L, 2018L, 2019L, 2017L, 2018L, 2019L), color = c("red", 
"red", "red", "", "", "", "orange", "orange", "orange")), class = "data.frame", 
row.names = c(NA, -9L))

df澄清，谢谢。
df$color谢谢，我很好奇苹果的颜色是否也是空的，我该怎么做？怎么知道“香蕉”是“黄色”，“苹果”是“红色”？是不是放在什么地方了？让我想想，如果有像“水果的颜色”这样的data.frame，它会有帮助吗？谢谢，我稍后再试。
color_fruit <- data.frame(fruit = c('apple', 'banana', 'orange'), 
              color = c('red', 'yellow', 'orange'), stringsAsFactors = FALSE)

df$color <- color_fruit$color[match(df$fruit, color_fruit$fruit)]
df

#   fruit year  color
#1  apple 2017    red
#2  apple 2018    red
#3  apple 2019    red
#4 banana 2017 yellow
#5 banana 2018 yellow
#6 banana 2019 yellow
#7 orange 2017 orange
#8 orange 2018 orange
#9 orange 2019 orange

merge(df, color_fruit, by = 'fruit')[-3]

df <- structure(list(fruit = c("apple", "apple", "apple", "banana", 
"banana", "banana", "orange", "orange", "orange"), year = c(2017L, 
2018L, 2019L, 2017L, 2018L, 2019L, 2017L, 2018L, 2019L), color = c("red", 
"red", "red", "", "", "", "orange", "orange", "orange")), class = "data.frame", 
row.names = c(NA, -9L))