Gegevens samenvatten

Exploratory Data Analysis in Python

Izzy Weber

Curriculum Manager, DataCamp

Groepen data verkennen

.groupby() groepeert data per categorie
De aggregatiefunctie geeft aan hoe je gegroepeerde data samenvat

books[["genre", "rating", "year"]].groupby("genre").mean()

|       genre |   rating |        year |
|-------------|----------|-------------|
|   Childrens | 4.780000 | 2015.075000 |
|     Fiction | 4.570229 | 2013.022901 |
| Non Fiction | 4.598324 | 2013.513966 |

Aggregatiefuncties

Som: .sum()
Aantal: .count()
Minimum: .min()
Maximum: .max()
Variantie: .var()
Standaarddeviatie: .std()

Ongeroepeerde data aggregeren

.agg() past aggregatiefuncties toe over een DataFrame

books[["rating", "year"]].agg(["mean", "std"])

|      |   rating |        year |
|------|----------|-------------|
| mean | 4.608571 | 2013.508571 |
|  std | 0.226941 |     3.28471 |

Aggregaties per kolom opgeven

books.agg({"rating": ["mean", "std"], "year": ["median"]})

|        |   rating |   year |
|--------|----------|--------|
|   mean | 4.608571 |    NaN |
|    std | 0.226941 |    NaN |
| median |      NaN | 2013.0 |

Benoemde samenvattingskolommen

books.groupby("genre").agg(
    mean_rating=("rating", "mean"),
    std_rating=("rating", "std"),
    median_year=("year", "median")
)

|  genre      | mean_rating | std_rating | median_year |
|-------------|-------------|------------|-------------|
|   Childrens |    4.780000 |   0.122370 |      2015.0 |
|     Fiction |    4.570229 |   0.281123 |      2013.0 |
| Non Fiction |    4.598324 |   0.179411 |      2013.0 |

Categorische samenvattingen visualiseren

sns.barplot(data=books, x="genre", y="rating")
plt.show()

een staafdiagram van boekgenres met hun gemiddelde beoordelingen

Laten we oefenen!

Exploratory Data Analysis in Python