在 apply 函数中使用库函数

Question

我有一个数据框，其中包含一个名为 'msgText' 的列，其中包含文本。为此，我想创建另一个名为 'wordcount' 的列来计算 'msgText' 的每一行包含的单词数。

该列如下所示：

head(all_transcripts$msgText)
[1]  "Hi, my name is Chris and I am a programmer"                                                                                                                                                                                                   
[2]  "I have worked with R for 12 years"                                                                                                                                                                                                                                                                                                                                                           
[3]  "Being a programmer I have many questions" 
[4]  "The fellow programmers at Whosebug help me to get the answer"                                                                                                                                                                                  
[5]  "This help has saved my life many times."                                                                                                                                                                                                                                                                                                                                                                                                        
[6]  "Thanks Whosebug!"

我想要的结果是：

head(all_transcripts$wordcount)
    [1]  10                                                                                                                                                                                                   
    [2]  8                                                                                                                                                                                                                                                                                                                                                           
    [3]  7 
    [4]  11                                                                                                                                                                                  
    [5]  8                                                                                                                                                                                                                                                                                                                                                                                                        
    [6]  2

为此，我将 ngram 库与 wordcount 函数结合使用。

我试过：

all_transcripts$wordcount <- apply(all_transcripts, 2, 
                                   wordcount(all_transcripts$msgText))

但是，这样做我得到了以下错误：

Error in match.fun(FUN) :    'wordcount(all_transcripts$msgText)' is
not a function, character or symbol

如何在不对数据集使用 for 循环的情况下正确使用 apply 函数？

Answer 1

我们可以遍历 'msgText' 的元素并应用 wordcount 函数

library(ngram)
library(tidyverse)
all_transcripts %>%
     mutate(wordcount = map_int(msgText, wordcount))
#                                                             msgText wordcount
#1                        Hi, my name is Chris and I am a programmer        10
#2                                 I have worked with R for 12 years         8
#3                          Being a programmer I have many questions         7
#4 The fellow programmers at Whosebug help me to get the answer        11
#5                           This help has saved my life many times.         8
#6                                             Thanks Whosebug!         2

或 base R

all_transcripts$wordcount <- sapply(all_transcripts$msgText, wordcount)

OP 代码中的问题是它循环遍历列（MARGIN = 2 in apply），其中向量 (alltranscripts$wordcount) 没有 dim属性

数据

all_transcripts <- structure(list(msgText = c("Hi, my name is Chris and I am a programmer", 
"I have worked with R for 12 years", "Being a programmer I have many questions", 
"The fellow programmers at Whosebug help me to get the answer", 
"This help has saved my life many times.", "Thanks Whosebug!"
)), class = "data.frame", row.names = c(NA, -6L))

Answer 2

考虑向量化 lengths 和 strsplit 以使用基数 R:

进行字数统计

all_transcripts$word_count <- lengths(strsplit(all_transcripts$text, split=" "))

all_transcripts

#                                                                text word_count
# 1                        Hi, my name is Chris and I am a programmer         10
# 2                                 I have worked with R for 12 years          8
# 3                          Being a programmer I have many questions          7
# 4 The fellow programmers at Whosebug help me to get the answer         11
# 5                           This help has saved my life many times.          8
# 6                                             Thanks Whosebug!          2

数据

all_transcripts <- data.frame(text=c("Hi, my name is Chris and I am a programmer",
                                     "I have worked with R for 12 years",
                                     "Being a programmer I have many questions",
                                     "The fellow programmers at Whosebug help me to get the answer",
                                     "This help has saved my life many times.",
                                     "Thanks Whosebug!"),
                              stringsAsFactors=FALSE)

在 apply 函数中使用库函数

Use a library function in the apply function

r

apply

word-count

dataframe

数据