Question

我有要列入矢量的列列表。列元素可以是名称或字符串“0”。我想获得一个列的元素列表，这些元素在名为df$keywords的字符向量中有一个名称。我在下面粘贴了一个示例数据框。我希望它成为

df$keywords[1,]将是一个空载体

df$keywords[2,]将是（ACT Science，study skills，MCAT）

任何帮助将不胜感激

    structure(list(V31 = structure(c(1L, 1L, 1L, 1L, 1L, 1L, 1L, 
    1L, 1L, 1L), .Label = "0", class = "factor"), V32 = structure(c(1L, 
    2L, 4L, 5L, 7L, 8L, 6L, 5L, 3L, 3L), .Label = c("0", "ACT Science", 
    "English", "Microsoft PowerPoint", "physics", "proofreading", 
    "reading", "writing"), class = "factor"), V33 = structure(c(1L, 
    1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L), .Label = "0", class = "factor"), 
    V34 = structure(c(1L, 7L, 5L, 5L, 8L, 2L, 6L, 5L, 3L, 4L), .Label = c("0", 
    "geography", "Italian", "literature", "prealgebra", "SAT reading", 
    "study skills", "trigonometry"), class = "factor"), V35 = structure(c(1L, 
    1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L), .Label = "0", class = "factor"), 
    V36 = structure(c(1L, 3L, 4L, 4L, 7L, 2L, 6L, 4L, 5L, 5L), .Label = c("0", 
    "English", "MCAT", "precalculus", "proofreading", "SAT writing", 
    "writing"), class = "factor"), V37 = structure(c(1L, 1L, 
    1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L), .Label = "0", class = "factor"), 
    V38 = structure(c(1L, 1L, 5L, 5L, 2L, 1L, 4L, 5L, 3L, 6L), .Label = c("0", 
    "English", "GED", "physical science", "reading", "spelling"
    ), class = "factor")), .Names = c("V31", "V32", "V33", "V34", 
    "V35", "V36", "V37", "V38"), class = "data.frame", row.names = c(NA, 
    -10L))

Answer 1

假设您的数据已分配到x，那么以下内容可实现我认为您所追求的目标：

apply(x, 1, function(r) {tmp <- unique(r); tmp[tmp != 0]})

apply适用于数据框的每一行，获取每行中的唯一元素并删除0个条目。结果是不同长度的向量列表，每行有唯一的非零元素。

Answer 2

在第一篇文章中，我没有正确理解所需的输出，A 稍微不同的方法是在这样的行中使用%in%运算符：

df$keywords <- apply(df,1, function(x) c( x[! x %in% "0"]))
df$keywords
#                                                                                                            keywords
#1                                                                                                                    
#2                                                    ACT Science, study skills, MCAT, ACT Science, study skills, MCAT
#3      Microsoft PowerPoint, prealgebra, precalculus, reading, Microsoft PowerPoint, prealgebra, precalculus, reading
#4                                physics, prealgebra, precalculus, reading, physics, prealgebra, precalculus, reading
#5                                    reading, trigonometry, writing, English, reading, trigonometry, writing, English
#6                                                            writing, geography, English, writing, geography, English
#7  proofreading, SAT reading, SAT writing, physical science, proofreading, SAT reading, SAT writing, physical science
#8                                physics, prealgebra, precalculus, reading, physics, prealgebra, precalculus, reading
#9                                            English, Italian, proofreading, GED, English, Italian, proofreading, GED
#10                           English, literature, proofreading, spelling, English, literature, proofreading, spelling

如果你想要每行unique套技能，只需添加命令unique，如下：

df$keywords <- apply(df,1, function(x) c( unique(x[ ! x %in% "0" ] ) ) )
df["keywords"]
#                                                  keywords
#1                                                          
#2                           ACT Science, study skills, MCAT
#3    Microsoft PowerPoint, prealgebra, precalculus, reading
#4                 physics, prealgebra, precalculus, reading
#5                   reading, trigonometry, writing, English
#6                               writing, geography, English
#7  proofreading, SAT reading, SAT writing, physical science
#8                 physics, prealgebra, precalculus, reading
#9                       English, Italian, proofreading, GED
#10              English, literature, proofreading, spelling

在R中组合列

2 个答案: