Power Metal: is it really about dragons?

Posted on 07 October 2018 in data-science

Some years ago, Matt Daniels [1] wrote a great article on who has the largest vocabulary in hip-hop. I thought it was brilliant: comparing Shakespeare to famous hip-hop artists. It got me thinking and gave me the inspiration of doing something similar with a genre I love: Power Metal. People know metal or heavy metal but not necessarily power metal. For me, power metal has speed (remember that last song on Guitar Hero), clean vocals (you can understand the words, looking at you grind metal) and lyrics about dragons. Here I will just confirm or infirm my assumption about dragons.

I used the lyrics of 58 bands, which should fall under the label of Power Metal, at least according to /r/powermetal [2] and myself. This article will dive into the vocabulary of the power metal bands, what makes a song power metal or not and who wrote the most positive and negative power metal songs ever (at least from my dataset).


  • Running Wild (2949 unique words) has the biggest vocabulary, followed by Helloween (2641) and Elvenking (2505),
  • Bands from Spain, Germany and Finland have an average of more than 1600 words vocabulary; in comparison native countries like UK, US and Scotland have an average of 925, 1383 and 1501 words respectively,
  • The most metal words are deliverance, defender, honour, forevermore, realm and the least are shit, baby, fuck, girl, verse,
  • The most negative song is Condemned To Hell by Gamma Ray and the most positive There's Something In The Skies by Dark Moor,
  • Source code: to be released soon,
  • Dataset: not available but you can find lyrics all over the internet ;)

The dataset

The dataset includes 58 bands: Alestorm, Angra, At Vance, Avantasia, Blind Guardian, Borealis, Cain’s Offering, Concerto Moon, Dark Moor, Demons & Wizards, Dragonforce, Dragonland, Dream Evil, Edguy, Elegy, Elvenking, Fairyland, Falconer, Firewind, Freedom Call, Gamma Ray, Gloryhammer, Grave Digger, Hammerfall, Heavenly, Helloween, Hibria, Highland Glory, Iron Savior, Judicator, Kamelot, Keldian, Labyrinth, Lost Horizon, Manowar, Masterplan, Nightwish, Nocturnal Rites, Orden Ogan, Pagan’s Mind, Pathfinder, Persuader, Power Quest, Powerwolf, Primal Fear, Rhapsody, Rhapsody Of Fire, Running Wild, Sabaton, Secret Sphere, Seventh Wonder, Sonata Arctica, Stratovarius, Theocracy, Twilight Force, Twilightning, Unisonic, Wisdom; and a total of 4808 songs in English.

Distribution of bands by country

Country Number of bands
Brazil 2
Canada 1
Finland 5
France 1
Germany 16
Greece 1
Hungary 1
Italy 5
Japan 1
Netherlands 1
Norway 3
Poland 1
Scotland 1
Spain 1
Sweden 10
UK 3
US 5

Bands from Germany and Sweden are over-represented compared to other countries. This is due to the dataset creation, which was mostly based on the albums recommendation of /r/powermetal. Therefore I won’t go deeper in regions difference.

Text analysis of the lyrics


Calculating the vocabulary length could be done in several ways: counting the unique words (with inflections, meaning singular, plural nouns, conjugated verbs, etc.), counting the lemma form of the words (more or less the dictionary form) and finally the stemmed version which is when you get the stem of a word (we reduce a word to the its minimal non-changing parts). There is no right way to do the counting. All the methods have their pros and cons:

  • stemming should be fast but the cutting might reduce to a stem common to two different words (ex: markets/marketing would give the stem market);
  • lemmatization requires knowing the part of speech (POS) which might slow your processing but would be more accurate.

Since I preferred fast results over a possible better accuracy, I chose the stemmed version (Porter) of the words for the vocabulary processing. Based on this stemming transformation, I could plot the following chart describing the growth of vocabulary range along the years (from 1982 to 2018).

Play with the slider it's interactive!

Largest vocabulary in PowerMetal in unique words* (in 2018)

  1. Running Wild (2949)
  2. Helloween (2641)
  3. Elvenking (2502)
  4. Sonata Arctica (2467)
  5. Edguy (2385)

* at least in my dataset

What makes a power metal song power metal?

We need to look at the importance of the words used in the song. Common metrics are tf (term frequency of a word), idf (inverse document frequency, how rare a word is in a document), tf-idf (term frequency-inverse document frequency, measuring how important a word is in a corpus)[3].

Iain Barr chose the tf approach and measured the Metalness of a word / lyrics as follow:

$$ M_w = \log \frac{freq^{metal-corpus}_w}{freq^{corpus}_w} $$

where $M_w$ is the Metalness of a word, $freq^{metal-corpus}_w$ the frequency of the word $w$ in the metal corpus, $freq^{corpus}_w$ the frequency of the word $w$ in another corpus.

He looked at the distribution of a specific word in two corpus - his metal lyrics dataset and the Brown corpus, an ensemble of literary texts from the 60s [4].

Nonetheless using a literary corpus might not be ideal since the type of text and choice of words between a novel and a lyric are quite different. I chose to use a dataset already prepared called Metrolyrics dataset, available on Kaggle [5].

After a bit of cleaning and processing, I got the following results (interactive chart):

A power metal is not necessarily about dragons (in the 47th position in the Metalness ranking): it’s all about deliverance, honour, defender, realm with a forevermore touch. Looking at the top 50 words, all these words wouldn’t appear out of place in a heroic fantasy novel or a dungeons & dragons handbook.

On the opposite, words like shit, baby, fuck, girl, verse are not that metal.

PowerMetalness ranking

The most power metal songs 🤘🤘🤘🤘🤘

  1. Freedom Call - 66 Warriors
  2. Grave Digger - The Emperor’s Death
  3. Manowar - Hail And Kill
  4. Dream Evil - Made Of Metal
  5. Primal Fear - Evil Spell

The least power metal songs 🤘

  1. Gamma Ray - Money
  2. Helloween - Anything My Mama Don't Like
  3. Iron Savior - Dance With Somebody (Mando Diao cover)
  4. Highland Glory - Love Gun (KISS cover)
  5. Masterplan - Black Dog (Led Zeppelin cover)

As you notice, the least power metal songs are mostly covers of non power metal bands, which makes sense.

If we look also at what words are the most important for each band, you will be able to distinguish what makes these bands unique. Let’s have a look at some iconic bands such as Alestorm, Manowar, Rhapsody and Sabaton.


Words: drink, sail, sea, pirate, quest
For a band which is part of the pirate metal genre, these words are the perfect representation of pirate-related vocabulary.


Words: die, ride, metal, live, fight
My knowledge of Manowar is a bit lacking but this iconic band seems to give importance to equally iconic words.


Words: holy, ancient, king, wind, land
One of my favorite bands. Their lyrics are epic and the most important words for them represent that.


Words: war, death, army, strike, way
Sabaton writes a lot about real wars and this is reflected in their top words.

Cluster bands by their lyrics

Lyrics can be used to find similarities between bands. To do so, I’m using hierarchical clustering, a clustering technique where you don’t need to already know the number of clusters in your data in advance.

Band clustering

Note that Rhapsody and Rhapsody of Fire are clustered together. For people who might not know, Rhapsody of Fire broke into in two bands, one keeping the original name and the other becoming Rhapsody. From a lyric point of view, as Luca Turilli wrote most if not all the songs for the bands, these two bands are basically the same which is confirmed in the clustering graph.

Out of this clustering emerge four clusters (interpretations my own, happy to hear yours):

  • Rhapsody-ish: uplifting epic and fantasy lyrics
  • Edguy-ish: wide range of lyrics (?)
  • Blind Guardian-ish: dark epic lyrics
  • Manowar-ish: brutal, powerful lyrics

Some bands are remotely affiliated with others:

  • Affiliated but independent: Gloryhammer with Rhapsody-ish, Alestorm with Manowar-ish
  • The outsider: Concerto Moon (Japanese band)

The cluster might be improved by looking at the topics of the lyrics and work from that.

Sentiment analysis

After having looked into the words, let’s feel them. I use VADER (Valence Aware Dictionary and sEntiment Reasoner) to analyze the sentiments in the lyrics. The datasets VADER was built upon include tweets, movie/amazon reviews and New York Times editorials. The authors claim that it’s “specifically attuned to sentiments expressed in social media” [6] but it shouldn’t impact much my analysis.

Positive sentiments

Out of 58 bands, only 20 bands were considered overall as positive. I’m not surprised by this as the lyrics in power metal are about epic themes which are not per se the most joyous theme.


The most positive songs in the dataset

  1. Dark Moor - There's Something In The Skies
  2. Sonata Arctica - I Have A Right
  3. Sonata Arctica - Half A Marathon Man
  4. Power Quest - Sacred Land
  5. Freedom Call - A Perfect Day


  1. Twilight Force
  2. Freedom Call
  3. Nightwish
  4. Fairyland
  5. Power Quest

Negative sentiments


The most negative songs in the dataset

  • Gamma Ray - Condemned To Hell
  • Dragonforce - War!
  • Sabaton - Burn In Hell
  • Edguy - Sacred Hell
  • Running Wild - Genocide

Just looking at the titles of the songs are enough to say we are not talking about bunnies and sweet cakes.


  • Sabaton
  • Judicator
  • Hibria
  • Dragonforce
  • Powerwolf


Power Metal is not that into dragons (47th rank). Indeed Power Metal has a fantasy and epic style where of course dragons don't clash with the theme. The project was fun to do and I discovered new bands along the way. There will be some updates on the analysis in the future, as I might add new bands and build on people’s feedbacks. I plan to release the source code I used for this analysis after some cleaning.

If you want me to add your favorite band(s), send me an email and I will try my best to add it/them!

Meanwhile keep 🤘!


  • Jorge, for the great comments and advice

Further reading


  1. https://pudding.cool/2017/02/vocabulary/index.html
  2. https://www.reddit.com/r/PowerMetal/wiki/essential
  3. https://en.wikipedia.org/wiki/Tf-idf
  4. https://www.degeneratestate.org/posts/2016/Apr/20/heavy-metal-and-natural-language-processing-part-1/
  5. https://www.kaggle.com/gyani95/380000-lyrics-from-metrolyrics
  6. https://github.com/cjhutto/vaderSentiment