Question

想要为语料库内的文档编写标签。标签存储在语料库外部的数据框中，具有特定的唯一文档ID。

挑战：（1）从数据帧中取出每个ID，（2）在语料库中找到相应的文档，（3）将标签从数据框设置为具有特定ID的语料库文档。

library("tm")
someID <- paste(letters[1:15], 16:30, sep="")
someTag <- sample(c("a","x","g","h","e"), 15, replace=TRUE)

data(crude) # a corpus with 20 docs
meta(crude, type="local", tag="someID") <- someID  # adding some additional IDs to the corpus

mydf <- data.frame(cbind(someTag, someID))  # Creating a dataframe with similar IDs
mydf <- mydf[sample(nrow(mydf)),]  # permutation of elements (rows)
rownames(mydf) <- 1:15  # overwriting the rownames

############################################
# doesn't work - my try - pseudocode

for (i in 1:nrow(mydf)){
          meta(crude[which(crude$someID==mydf$someID[i])], tag="someTag", type="local") <- mydf$someTag[i]
    }

############################################
# How the data looks like:

mydf
# R output:
> mydf
   someTag someID
1        h    l27
2        x    g22
3        h    d19
4        a    e20
5        h    i24
6        x    j25
7        h    o30
8        x    n29
9        e    h23
10       x    m28
11       h    k26
12       e    c18
13       a    a16
14       e    b17
15       x    f21

meta(crude[1], type="local")
# R output:
> meta(crude[1], type="local")
Available meta data pairs are:
  Author       : 
  DateTimeStamp: 1987-02-26 17:00:56
  Description  : 
  Heading      : DIAMOND SHAMROCK (DIA) CUTS CRUDE PRICES
  ID           : 127
  Language     : en
  Origin       : Reuters-21578 XML
User-defined local meta data pairs are:
$TOPICS
[1] "YES"

$LEWISSPLIT
[1] "TRAIN"

$CGISPLIT
[1] "TRAINING-SET"

$OLDID
[1] "5670"

$Topics
[1] "crude"

$Places
[1] "usa"

$People
character(0)

$Orgs
character(0)

$Exchanges
character(0)

$someID
[1] "a16"

感谢您的帮助（;

Answer 1

根据？meta

meta(crude, type="local", tag="someID") <- someID

将在单个文档级别分配元数据标记someID。您想要的是在集合级别创建标记。为此，您希望操纵语料库的DMetaData属性。你可以这样做：

meta(crude, type="indexed", tag="someID") <- someID

但我发现使用访问

更容易

DMetaData(crude)$someID  <- someID

（这至少适用于VCorpus类型的语料库）。通过这种调整：

library("tm")
someID <- paste(letters[1:15], 16:30, sep="")
someTag <- sample(c("a","x","g","h","e"), 15, replace=TRUE)

data(crude) # a corpus with 20 docs
# Need to be sure to allocate full tag and id set.
DMetaData(crude)$someID <- c(someID,rep(NA,5))
DMetaData(crude)$someTag <- rep(NA,20)

mydf <- data.frame(cbind(someTag, someID), stringsAsFactors=FALSE)  # Creating a dataframe with similar IDs
mydf <- mydf[sample(nrow(mydf)),]  # permutation of elements (rows)
rownames(mydf) <- 1:15  # overwriting the rownames

for (i in 1:nrow(mydf)){
      DMetaData(crude)$someTag[DMetaData(crude)$someID==mydf$someID[i]]<- mydf$someTag[i]
    }

结果：

> DMetaData(crude)
   MetaID someID someTag  
1       0    a16       a
2       0    b17       h
3       0    c18       g
4       0    d19       a
5       0    e20       e
6       0    f21       a
7       0    g22       x
8       0    h23       g
9       0    i24       h
10      0    j25       e
11      0    k26       x
12      0    l27       a
13      0    m28       a
14      0    n29       h
15      0    o30       a
16      0   <NA>    <NA>
17      0   <NA>    <NA>
18      0   <NA>    <NA>
19      0   <NA>    <NA>
20      0   <NA>    <NA>

R：通过ID-tag查找语料库文档并设置其他标签

1 个答案: