从R语句中提取数值数据？

Question

我工作（R与openNLP）从提供的语句中提取数字数据。

的语句是"The room temperature is 37 to 39 C. The Air flow is near 80 cfm".

这里的预期输出"Temperature > 37 - 39c","Air flow -> 80cfm"。

你可以建议POS标签上的任何正则表达式模式来获得名词（NN）和下一个可用的数字数据（CD）吗？

是否有任何替代方法来提取类似的数据？

Answer 1

从自然文本中提取数据很难！我预计这个解决方案会很快破解。但是，这是一种让你开始的方法。你没有提供整个标记的句子，所以我插入了我自己的标签。您可能需要更改此标签。此外，此代码既不高效也不是矢量化的，只能用于单个字符串。

library(stringr) 

text <- "The_DT room_NN temperature_NN is_VBZ 37_CD to_PRP 39_CD C_NNU. The_DT Air_NN flow_NN is_VBZ near_ADV 80_CD cfm_NNU" 

# find the positions where a Number appears; it may be followed by prepositions, units and other numbers 
matches <- gregexpr("(\\w+_CD)+(\\s+\\w+_(NNU|PRP|CD))*", text, perl=TRUE) 

mapply(function(position, length) { 
    # extract all NN sequences 
    nouns <- text %>% str_sub(start = 1, end = position) %>% 
     str_extract_all("\\w+_NN(\\s+\\w+_NN)*") 
    # get Numbers 
    nums <- text %>% str_sub(start=position, end = position + length) 
    # format output string 
    result <- paste(tail(nouns[[1]], n=1), nums, sep = " > ") 
    # clean tags 
    gsub("_\\w+", "", result) 
}, matches[[1]], attr(matches[[1]], "match.length")) 
# output: [1] "room temperature > 37 to 39 C." "Air flow > 80 cfm" 

Answer 2

也许你可以从下面的方法开始。希望这可以帮助！

library(NLP) 
library(openNLP) 
library(dplyr) 

s <- "The room temperature is 37 to 39 C. The Air flow is near 80 cfm" 
sent_token_annotator <- Maxent_Sent_Token_Annotator() 
word_token_annotator <- Maxent_Word_Token_Annotator() 
a2 <- annotate(s, list(sent_token_annotator, word_token_annotator)) 
pos_tag_annotator <- Maxent_POS_Tag_Annotator() 
a3 <- annotate(s, pos_tag_annotator, a2) 
#distribution of POS tags for word tokens 
a3w <- subset(a3, type == "word") 

#select consecutive NN & CD POS 
a3w_temp <- a3w[sapply(a3w$features, function(x) x$POS == "NN" | x$POS == "CD")] 
a3w_temp_df <- as.data.frame(a3w_temp) 
#add lead 'features' to dataframe and select rows having (NN, CD) or (NN, CD, CD) sequence 
a3w_temp_df$ahead_features = lead(a3w_temp_df$features,1) 
a3w_temp_df$features_comb <- paste(a3w_temp_df$features,a3w_temp_df$ahead_features) 
l <- row.names(subset(a3w_temp_df, features_comb == "list(POS = \"NN\") list(POS = \"CD\")" | 
     features_comb == "list(POS = \"CD\") list(POS = \"CD\")")) 
l_final <- sort(unique(c(as.numeric(l), as.numeric(l) +1))) 
a3w_df <- a3w_temp_df[l_final,] 

#also include POS which is immediately after CD 
idx <- a3w_df[a3w_df$features=="list(POS = \"CD\")","id"]+1 
idx <- sort(c(idx,a3w_df$id)) 
op = paste(strsplit(s, split = " ")[[1]][idx -1], collapse = " ") 
op 

输出是：

[1] "temperature 37 to 39 C. flow 80 cfm"