将Quanteda包中的dfmSparse转换为R中的数据帧或数据表

Question

我有一个dfmSparse对象(大,2.1GB),它被标记化并使用ngrams(unigrams,bigrams,trigrams和fourgrams),我想将它转换为数据框或数据表对象的列:内容和频率.

我试图取消列出......但没有奏效.我是NLP的新手,我不知道使用的方法,我没有想法,也没有在这里或谷歌找到解决方案.

有关数据的一些信息:

>str(tokfreq)
Formal class 'dfmSparse' [package "quanteda"] with 11 slots
  ..@ settings    :List of 1
  .. ..$ : NULL
  ..@ weighting   : chr "frequency"
  ..@ smooth      : num 0
  ..@ ngrams      : int [1:4] 1 2 3 4
  ..@ concatenator: chr "_"
  ..@ Dim         : int [1:2] 167500 19765478
  ..@ Dimnames    :List of 2
  .. ..$ docs    : chr [1:167500] "character(0).content" "character(0).content" "character(0).content" "character(0).content" ...
  .. ..$ features: chr [1:19765478] "add" "lime" "juice" "tequila" ...
  ..@ i           : int [1:54488417] 0 75 91 178 247 258 272 327 371 391 ...
  ..@ p           : int [1:19765479] 0 3218 3453 4015 4146 4427 4637 140665 140736 142771 ...
  ..@ x           : num [1:54488417] 1 1 1 1 5 1 1 1 1 1 ...
  ..@ factors     : list()

>summary(tokfreq)
       Length         Class          Mode 
3310717565000     dfmSparse            S4

谢谢!

编辑:这是我从语料库创建数据集的方式:

# tokenize
tokenized <- tokenize(x = teste, ngrams = 1:4)
# Creating the dfm
tokfreq <- dfm(x = tokenized)

Answer 1

如果我理解你关于"内容"和"频率"的含义的问题,我们应该这样做.请注意,在此方法中,data.frame不大于稀疏矩阵,因为您只记录总计数,而不是存储文档行分布.

myDfm <- dfm(data_corpus_inaugural, ngrams = 1:4, verbose = FALSE)
head(myDfm)
## Document-feature matrix of: 57 documents, 314,224 features.
## (showing first 6 documents and first 6 features)
##                  features
## docs              fellow-citizens  of the senate and house
##   1789-Washington               1  71 116      1  48     2
##   1793-Washington               0  11  13      0   2     0
##   1797-Adams                    3 140 163      1 130     0
##   1801-Jefferson                2 104 130      0  81     0
##   1805-Jefferson                0 101 143      0  93     0
##   1809-Madison                  1  69 104      0  43     0

# convert to a data.frame
df <- data.frame(Content = featnames(myDfm), Frequency = colSums(myDfm), 
                 row.names = NULL, stringsAsFactors = FALSE)
head(df)
##           Content Frequency
## 1 fellow-citizens        39
## 2              of      7055
## 3             the     10011
## 4          senate        15
## 5             and      5233
## 6           house        11
tail(df)
##                           Content Frequency
## 314219         and_may_he_forever         1
## 314220       may_he_forever_bless         1
## 314221     he_forever_bless_these         1
## 314222 forever_bless_these_united         1
## 314223  bless_these_united_states         1
## 314224     these_united_states_of         1    

object.size(df)
## 25748240 bytes
object.size(myDfm)
## 29463592 bytes

新增2018-02-25

在quanteda > = 1.0.0中,有一个函数textstat_frequency()可以生成所需的data.frame,例如

textstat_frequency(data_dfm_lbgexample) %>% head()
#   feature frequency rank docfreq group
# 1       P       356    1       5   all
# 2       O       347    2       4   all
# 3       Q       344    3       5   all
# 4       N       317    4       4   all
# 5       R       316    5       4   all
# 6       S       280    6       4   all