In [1]:

import pandas as pd

In [2]:

wide_form = pd.DataFrame(
    {
        "Species": ["arctic fox", "walrus", "reindeer", "polar bear", "seal"],
        "Observation site A": [3, 0, 0, 1, 2],
        "Observation site B": [1, 1, 10, 0, 1],
        "Observation site C": [0, 1, 1, 1, 2],
    }
)

wide_form

Out[2]:

	Species	Observation site A	Observation site B	Observation site C
0	arctic fox	3	1	0
1	walrus	0	1	1
2	reindeer	0	10	1
3	polar bear	1	0	1
4	seal	2	1	2

In [3]:

long_form = wide_form.melt("Species", var_name="Site", value_name="Number of sightings")

long_form

Out[3]:

	Species	Site	Number of sightings
0	arctic fox	Observation site A	3
1	walrus	Observation site A	0
2	reindeer	Observation site A	0
3	polar bear	Observation site A	1
4	seal	Observation site A	2
5	arctic fox	Observation site B	1
6	walrus	Observation site B	1
7	reindeer	Observation site B	10
8	polar bear	Observation site B	0
9	seal	Observation site B	1
10	arctic fox	Observation site C	0
11	walrus	Observation site C	1
12	reindeer	Observation site C	1
13	polar bear	Observation site C	1
14	seal	Observation site C	2

In [4]:

long_form.pivot(
    index="Species", columns="Site", values="Number of sightings"
).reset_index()

Out[4]:

Site	Species	Observation site A	Observation site B	Observation site C
0	arctic fox	3	1	0
1	polar bear	1	0	1
2	reindeer	0	10	1
3	seal	2	1	2
4	walrus	0	1	1