Scatter plots in Pandas - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of a basic scatter plot code

What will be the output of this code snippet that creates a scatter plot using pandas and matplotlib?

Pandas

import pandas as pd
import matplotlib.pyplot as plt

data = {'x': [1, 2, 3, 4], 'y': [10, 20, 25, 30]}
df = pd.DataFrame(data)
df.plot.scatter(x='x', y='y')
plt.show()

A A scatter plot with points at coordinates (1,10), (2,20), (3,25), (4,30) displayed

B A line plot connecting points (1,10), (2,20), (3,25), (4,30) displayed

C A bar chart with bars at x=1,2,3,4 with heights 10,20,25,30 displayed

D SyntaxError due to missing plt.scatter call

💡 Hint

Remember that df.plot.scatter creates a scatter plot, not a line or bar chart.

The code uses pandas DataFrame's plot.scatter method which creates a scatter plot with the given x and y columns. plt.show() displays the plot.

❓ data_output

intermediate

Number of points in scatter plot

Given this DataFrame and scatter plot code, how many points will appear in the scatter plot?

Pandas

import pandas as pd

data = {'height': [150, 160, 170, 180, 190], 'weight': [50, 60, 65, 80, 90]}
df = pd.DataFrame(data)
df.plot.scatter(x='height', y='weight')

A 6

B 4

C 0

D 5

💡 Hint

Each row in the DataFrame corresponds to one point in the scatter plot.

The DataFrame has 5 rows, so the scatter plot will have 5 points.

🔧 Debug

advanced

Identify the error in scatter plot code

What error will this code raise when trying to create a scatter plot?

Pandas

import pandas as pd
import matplotlib.pyplot as plt

data = {'a': [1, 2, 3], 'b': [4, 5, 6]}
df = pd.DataFrame(data)
df.plot.scatter(x='x', y='b')
plt.show()

A TypeError: unsupported operand type(s)

B ValueError: x and y must be numeric

C KeyError: 'x'

D No error, plot displays correctly

💡 Hint

Check if the DataFrame has a column named 'x'.

The DataFrame does not have a column named 'x', so trying to plot with x='x' raises a KeyError.

❓ visualization

advanced

Effect of color parameter in scatter plot

What will be the color of points in the scatter plot created by this code?

Pandas

import pandas as pd
import matplotlib.pyplot as plt

data = {'x': [1, 2, 3], 'y': [4, 5, 6]}
df = pd.DataFrame(data)
df.plot.scatter(x='x', y='y', c='red')
plt.show()

A Points will have default blue color

B All points will be red

C Points will be green

D SyntaxError due to invalid color argument

💡 Hint

The color parameter sets the color of all points.

The color='red' argument sets all scatter plot points to red color.

🚀 Application

expert

Interpreting scatter plot with categorical color grouping

Given this DataFrame and scatter plot code, what does the color grouping represent in the plot?

Pandas

import pandas as pd
import matplotlib.pyplot as plt

data = {'age': [25, 30, 22, 40, 35], 'income': [50000, 60000, 45000, 80000, 70000], 'gender': ['M', 'F', 'F', 'M', 'F']}
df = pd.DataFrame(data)
df.plot.scatter(x='age', y='income', c=df['gender'].map({'M': 'blue', 'F': 'pink'}))
plt.show()

A Blue points represent males, pink points represent females

B Blue points represent females, pink points represent males

C Colors represent income levels, blue for high income, pink for low income

D Colors represent age groups, blue for younger, pink for older

💡 Hint

Look at how the 'gender' column is mapped to colors.

The code maps 'M' to blue and 'F' to pink, so blue points are males and pink points are females.