Question

我正在尝试从数据框中删除包含少于5个字的行。例如

mydf <- as.data.frame(read.xlsx("C:\\data.xlsx", 1, header=TRUE)

head(mydf)

     NO    ARTICLE
1    34    The New York Times reports a lot of words here.
2    12    Greenwire reports a lot of words.
3    31    Only three words.
4     2    The Financial Times reports a lot of words.
5     9    Greenwire short.
6    13    The New York Times reports a lot of words again.

我想删除5个或更少单词的行。我怎么能这样做？

Answer 1

以下是两种方式：

mydf[sapply(gregexpr("\\W+", mydf$ARTICLE), length) >4,]
#   NO                                          ARTICLE
# 1 34  The New York Times reports a lot of words here.
# 2 12                Greenwire reports a lot of words.
# 4  2      The Financial Times reports a lot of words.
# 6 13 The New York Times reports a lot of words again.


mydf[sapply(strsplit(as.character(mydf$ARTICLE)," "),length)>5,]
#   NO                                          ARTICLE
# 1 34  The New York Times reports a lot of words here.
# 2 12                Greenwire reports a lot of words.
# 4  2      The Financial Times reports a lot of words.
# 6 13 The New York Times reports a lot of words again.

第一个生成一个向量，包含第一个之后每个单词的起始位置，然后计算该向量的长度。

第二个将ARTICLE列拆分为包含组成单词的向量，并计算该向量的长度。这可能是一种更好的方法。

Answer 2

qdap包中的字数（wc）函数也可以促进这一点：

dat <- read.transcript(text="34    The New York Times reports a lot of words here.
12    Greenwire reports a lot of words.
31    Only three words.
2    The Financial Times reports a lot of words.
9    Greenwire short.
13    The New York Times reports a lot of words again.", 
    col.names = qcv(NO, ARTICLE), sep="   ")

library(qdap)
dat[wc(dat$ARTICLE) > 4, ]

##   NO                                          ARTICLE
## 1 34  The New York Times reports a lot of words here.
## 2 12                Greenwire reports a lot of words.
## 4  2      The Financial Times reports a lot of words.
## 6 13 The New York Times reports a lot of words again.

如何从R中只包含少量单词的数据框中删除行？

2 个答案: