如何计算 Pandas DataFrame？

Question

import pandas as pd

# Read CSV data file:
df = pd.read_csv('~/nclab-data-read/titanic.csv')

# Port where most passengers embarked:
port = df['Embarked'].mode()[0]
**# Count these passengers:
n_port = df[['Name']].loc[df['Embarked'] == 1].count()[0]**

I believe I have something incorrect in the bottom row, but can't figure out what.

Answer 1

count() returns the number of non-null values. If applied to a DataFrame, it returns an array with 1 value per column (hence you need to take the index 0).

When applied to a Series, you get the number directly.

n_port = df.loc[df['Embarked'] == 1, 'Name'].count()

Obviously, both lines will return the same result.