Exploring Palmer Penguins with Python

The data comes from the Palmer Penguins project.

License: CC0 (Creative Commons Zero)

Citation: Horst AM, Hill AP, Gorman KB (2020). palmerpenguins: Palmer Archipelago (Antarctica) penguin data. R package version 0.1.0. doi: 10.5281/zenodo.3960218.

import altair as alt
from palmerpenguins import load_penguins

penguins = load_penguins()
penguins.head()

	species	island	bill_length_mm	bill_depth_mm	flipper_length_mm	body_mass_g	sex	year
0	Adelie	Torgersen	39.1	18.7	181.0	3750.0	male	2007
1	Adelie	Torgersen	39.5	17.4	186.0	3800.0	female	2007
2	Adelie	Torgersen	40.3	18.0	195.0	3250.0	female	2007
3	Adelie	Torgersen	NaN	NaN	NaN	NaN	NaN	2007
4	Adelie	Torgersen	36.7	19.3	193.0	3450.0	female	2007

I first compared the average body mass of each species.

penguins.groupby("species")["body_mass_g"].mean()

species
Adelie       3700.662252
Chinstrap    3733.088235
Gentoo       5076.016260
Name: body_mass_g, dtype: float64

Gentoo penguins have the highest average body mass of the three species.

Next, I looked at the relationship between flipper length and body mass.

alt.Chart(penguins).mark_point().encode(
    x=alt.X(
        "flipper_length_mm:Q",
        scale=alt.Scale(domain=[170, 235]),
        title="Flipper length (mm)"
    ),
    y=alt.Y(
        "body_mass_g:Q",
        scale=alt.Scale(domain=[2500, 6500]),
        title="Body mass (g)"
    ),
    color="species:N"
).properties(
    width=600,
    height=400
)

Figure 1: Relationship between flipper length and body mass across penguin species.

The plot shows that penguins with longer flippers tend to have greater body mass.

Finally, I calculated the correlation between flipper length and body mass for each species.

(penguins
.groupby("species")
.apply( lambda x: x["flipper_length_mm"].corr(x["body_mass_g"]))
)

species
Adelie       0.468202
Chinstrap    0.641559
Gentoo       0.702667
dtype: float64

The correlations are positive for all three species, showing that the relationship between longer flippers and greater body mass is also present within each species, not just across the full dataset.