Quanteda：带有新文本和旧词汇的dtm

如何解决Quanteda：带有新文本和旧词汇的dtm

我使用Quanteda构建文档术语矩阵：

DELETE

哪个产量：

library(quanteda)
mytext = "This is my old text"
dtm <- dfm(mytext,tolower=T)
convert(dtm,to="data.frame")

我需要使“新”文本（新语料库）适合我现有的dtm（使用相同的词汇，以便出现相同的矩阵列）

假设我的“新”文本/语料是：

  doc_id this is my old text
1  text1    1  1  1   1    1

我如何使这个“新”文本/语料库适合现有的dtm词汇表，以便得到一个像这样的矩阵：

newtext = "This is my new text"

解决方法

在转换为data.frame之前，您需要dfm_match()。

library(quanteda)
## Package version: 2.1.2

mytext <- c(oldtext = "This is my old text")
dtm_old <- dfm(mytext)
dtm_old
## Document-feature matrix of: 1 document,5 features (0.0% sparse).
##          features
## docs      this is my old text
##   oldtext    1  1  1   1    1

newtext <- c(newtext = "This is my new text")
dtm_new <- dfm(newtext)
dtm_new
## Document-feature matrix of: 1 document,5 features (0.0% sparse).
##          features
## docs      this is my new text
##   newtext    1  1  1   1    1

要进行匹配，请使用dfm_match()使新dfm与旧功能的功能集和顺序保持一致：

dtm_matched <- dfm_match(dtm_new,featnames(dtm_old))
dtm_matched
## Document-feature matrix of: 1 document,5 features (20.0% sparse).
##          features
## docs      this is my old text
##   newtext    1  1  1   0    1

convert(dtm_matched,to = "data.frame")
##    doc_id this is my old text
## 1 newtext    1  1  1   0    1