how to count the occurences of a value

Question

How to count the number of occurences for a histogram using dataframes

d = {'color': ["blue", "green", "yellow", "red, blue", "green, yellow", "yellow, red, blue"],}
df = pd.DataFrame(data=d)

How do you go from

color
blue
green
yellow
red, blue
green, yellow
yellow, red, blue

to

color	occurance
blue	3
green	2
yellow	3

Answer 1

Let's try split by regex ,s\* for comma with zero or more whitespaces, then explode into rows and value_counts to get the count of values:

s = (
    df['color'].str.split(r',\s*')
        .explode()
        .value_counts()
        .rename_axis('color')
        .reset_index(name='occurance')
)

Or can split and expand then stack:

s = (
    df['color'].str.split(r',\s*', expand=True)
        .stack()
        .value_counts()
        .rename_axis('color')
        .reset_index(name='occurance')
)

s:

    color  occurance
0    blue          3
1  yellow          3
2   green          2
3     red          2