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Aprenda Adding new Columns | Basics of Dataframes
Pandas: First Steps

bookAdding new Columns

We can easily add new columns to an existing DataFrame using the indexing syntax:

dataframe[column_name] = values

It is important that if values is a list, it needs to have the same number of elements as there are rows in the DataFrame, otherwise you'll get an error. Alternatively, we can assign a single value to the entire new column as well.

Example 1: New Column from a Single Value

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import pandas as pd df = pd.DataFrame({ 'Product': ['Laptop', 'Tablet', 'Phone'], 'Old Price': [1000, 600, 400] }) # Add a new column with a fixed price for all rows df['New Price'] = 700 print(df)
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Example 2: New Column using a List of Values

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import pandas as pd df = pd.DataFrame({ 'Member': ['Sophie', 'Liam', 'Emma'], 'Role': ['Designer', 'Developer', 'Tester'] }) # Add a new column for Project Name df['Project'] = ['Marketing Website Redesign', 'Client Portal Backend Development', 'Payment Flow QA Testing'] print(df)
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Example 3: New Column derived from Another Column

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import pandas as pd df = pd.DataFrame({ 'Product': ['Laptop', 'Tablet', 'Phone'], 'Price': [1000, 600, 400] }) # Derive a new column 'Discounted Price' (10% off) df['Discounted Price'] = df['Price'] * 0.9 print(df)
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1. What happens if you try to add a new column to a DataFrame with a list that has fewer elements than the number of rows?

2. Which of the following lines correctly adds a column Discount which is 20% of the Price?

3. What would be the output of the following code?

question mark

What happens if you try to add a new column to a DataFrame with a list that has fewer elements than the number of rows?

Select the correct answer

question mark

Which of the following lines correctly adds a column Discount which is 20% of the Price?

Select the correct answer

question mark

What would be the output of the following code?

Select the correct answer

Tudo estava claro?

Como podemos melhorá-lo?

Obrigado pelo seu feedback!

Seção 2. Capítulo 5

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bookAdding new Columns

Deslize para mostrar o menu

We can easily add new columns to an existing DataFrame using the indexing syntax:

dataframe[column_name] = values

It is important that if values is a list, it needs to have the same number of elements as there are rows in the DataFrame, otherwise you'll get an error. Alternatively, we can assign a single value to the entire new column as well.

Example 1: New Column from a Single Value

1234567891011
import pandas as pd df = pd.DataFrame({ 'Product': ['Laptop', 'Tablet', 'Phone'], 'Old Price': [1000, 600, 400] }) # Add a new column with a fixed price for all rows df['New Price'] = 700 print(df)
copy

Example 2: New Column using a List of Values

1234567891011
import pandas as pd df = pd.DataFrame({ 'Member': ['Sophie', 'Liam', 'Emma'], 'Role': ['Designer', 'Developer', 'Tester'] }) # Add a new column for Project Name df['Project'] = ['Marketing Website Redesign', 'Client Portal Backend Development', 'Payment Flow QA Testing'] print(df)
copy

Example 3: New Column derived from Another Column

1234567891011
import pandas as pd df = pd.DataFrame({ 'Product': ['Laptop', 'Tablet', 'Phone'], 'Price': [1000, 600, 400] }) # Derive a new column 'Discounted Price' (10% off) df['Discounted Price'] = df['Price'] * 0.9 print(df)
copy

1. What happens if you try to add a new column to a DataFrame with a list that has fewer elements than the number of rows?

2. Which of the following lines correctly adds a column Discount which is 20% of the Price?

3. What would be the output of the following code?

question mark

What happens if you try to add a new column to a DataFrame with a list that has fewer elements than the number of rows?

Select the correct answer

question mark

Which of the following lines correctly adds a column Discount which is 20% of the Price?

Select the correct answer

question mark

What would be the output of the following code?

Select the correct answer

Tudo estava claro?

Como podemos melhorá-lo?

Obrigado pelo seu feedback!

Seção 2. Capítulo 5
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