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quanteda.sentiment

Installation

You can install quanteda.sentiment from GitHub with:

remotes::install_github("quanteda/quanteda.sentiment")

The package is not yet on CRAN.

About

quanteda.sentiment extends the quanteda package with functions for computing sentiment on text. It has two main functions, for computing two types of sentiment. These follow the structure of a quanteda dictionary, which consists of key entries expressing the canonical concept, and value patterns (such as “good”, “sad*“, etc.) to be matched in a text and counted as occurrences of that key.

The approach to sentiment in this package approaches sentiment computation in two ways, depending on whether sentiment is considered a key attribute, in which case the keys are assigned a polarity such as positive or negative, or whether individual values are assigned a valence, in the form of some continuous value indicating a degree of sentiment. Each is implemented in a separate function:

• Polarity-based sentiment. This is implemented via textstat_polarity(), for computing a sentiment based on keys set as “poles” of positive versus negative sentiment. Setting polarity is dones through the polarity()<- function and can be set for any dictionary, for any keys. “Sentiment” here can be broadly construed as any contrasting pair of poles, such as “Democrat” versus “Republican”, for instance. More than one key can be associated with the same pole.

  Polar values are converted into sentiment scores using a flexible function, such as $\mathrm{log}(pos / neg)$, or $(pos - neg)/(pos + neg)$. quanteda.sentiment offers three built-in functions, but the user can supply any function for combining polarities.

• Valence-based sentiment. This is implemented via textstat_valence(), for computing sentiment as the average valence of a document’s words, based on a dictionary whose values have numeric valence scores. Valence scores are set using the valence()<- function. Each key in a dictionary may have values with difference valences.

The package comes with the following built-in dictionaries:

Examples

For a polarity dictionary, we can use the positive and negative key categories from the General Inquirer dictionary:

library("quanteda.sentiment")
## Loading required package: quanteda
## Package version: 4.0.0
## Unicode version: 14.0
## ICU version: 71.1
## Parallel computing: 10 of 10 threads used.
## See https://quanteda.io for tutorials and examples.
## 
## Attaching package: 'quanteda.sentiment'
## The following object is masked from 'package:quanteda':
## 
##     data_dictionary_LSD2015

# inspect the dictionary and its polarities
print(data_dictionary_geninqposneg, max_nval = 8)
## Dictionary object with 2 key entries.
## Polarities: pos = "positive"; neg = "negative" 
## - [positive]:
##   - abide, ability, able, abound, absolve, absorbent, absorption, abundance [ ... and 1,645 more ]
## - [negative]:
##   - abandon, abandonment, abate, abdicate, abhor, abject, abnormal, abolish [ ... and 2,002 more ]

# compute sentiment
tail(data_corpus_inaugural) |>
  textstat_polarity(dictionary = data_dictionary_geninqposneg)
##       doc_id sentiment
## 1  2001-Bush 0.9233579
## 2  2005-Bush 0.9829457
## 3 2009-Obama 0.5666378
## 4 2013-Obama 0.7597420
## 5 2017-Trump 0.7724428
## 6 2021-Biden 0.6018714

For a valence dictionary, we can compute this for the “pleasure” category of the Affective Norms for English Words (ANEW):

library("quanteda", warn.conflicts = FALSE, quietly = TRUE)
library("quanteda.sentiment")

# inspect the dictionary and its valences
print(data_dictionary_ANEW, max_nval = 8)
## Dictionary object with 3 key entries.
## Valences set for keys: pleasure, arousal, dominance 
## - [pleasure]:
##   - abduction, able, abortion, absent, absurd, abundance, abuse, accept [ ... and 2,463 more ]
## - [arousal]:
##   - abduction, able, abortion, absent, absurd, abundance, abuse, accept [ ... and 2,463 more ]
## - [dominance]:
##   - abduction, able, abortion, absent, absurd, abundance, abuse, accept [ ... and 2,463 more ]
lapply(valence(data_dictionary_ANEW), head, 8)
## $pleasure
## abduction      able  abortion    absent    absurd abundance     abuse    accept 
##      2.76      6.74      3.50      3.69      4.26      6.59      1.80      6.80 
## 
## $arousal
## abduction      able  abortion    absent    absurd abundance     abuse    accept 
##      5.53      4.30      5.39      4.73      4.36      5.51      6.83      5.53 
## 
## $dominance
## abduction      able  abortion    absent    absurd abundance     abuse    accept 
##      3.49      6.83      4.59      4.35      4.73      5.80      3.69      5.41

# compute the sentiment
tail(data_corpus_inaugural) |>
  textstat_valence(dictionary = data_dictionary_ANEW["pleasure"])
##       doc_id sentiment
## 1  2001-Bush  6.091330
## 2  2005-Bush  6.308839
## 3 2009-Obama  5.841437
## 4 2013-Obama  6.045129
## 5 2017-Trump  6.223944
## 6 2021-Biden  6.018528

We can compare two measures computed in different ways (although they are not comparable, really, since they are different lexicons):

# ensure we have this package's version of the dictionary
data("data_dictionary_LSD2015", package = "quanteda.sentiment")

sent_pol <- tail(data_corpus_inaugural, 25) |>
  textstat_polarity(dictionary = data_dictionary_LSD2015)
sent_pol <- dplyr::mutate(sent_pol, polarity = sentiment)
sent_val <- tail(data_corpus_inaugural, 25) |>
  textstat_valence(dictionary = data_dictionary_AFINN)

library("ggplot2")

ggplot(data.frame(sent_pol, valence = sent_val$sentiment),
       aes(x = polarity, y = valence)) +
  geom_point()

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Good enough for government work!

Where to learn more

Each dictionary and function has extensive documentation, including references to social scientific research articles where each sentiment concept is described in detail. There is also a package vignette with more detailed examples.