pandas找出唯一值

import pandas as pd

# 创建一个DataFrame
data = {'id': [1, 2, 3, 4, 1, 2, 3],
        'name': ['Alice', 'Bob', 'Charlie', 'David', 'Alice', 'Bob', 'Charlie']}
df = pd.DataFrame(data)

# 找出'name'列的唯一值
unique_names = df['name'].unique()
print(unique_names)

['Alice' 'Bob' 'Charlie' 'David']

import pandas as pd

# 创建一个DataFrame
data = {'id': [1, 2, 3, 4, 1, 2, 3],
        'name': ['Alice', 'Bob', 'Charlie', 'David', 'Alice', 'Bob', 'Charlie']}
df = pd.DataFrame(data)

# 找出'name'列的唯一值的数量
num_unique_names = df['name'].nunique()
print(num_unique_names)

4

import pandas as pd

# 创建一个DataFrame
data = {'id': [1, 2, 3, 4, 1, 2, 3],
        'name': ['Alice', 'Bob', 'Charlie', 'David', 'Alice', 'Bob', 'Charlie'],
        'age': [25, 30, 35, 40, 25, 30, 35]}
df = pd.DataFrame(data)

# 找出所有列的唯一值
for col in df.columns:
    unique_values = df[col].unique()
    print(f'Unique values in column {col}: {unique_values}')

Unique values in column id: [1 2 3 4]
Unique values in column name: ['Alice' 'Bob' 'Charlie' 'David']
Unique values in column age: [25 30 35 40]