Python Function Introduction and an Inch-Centimeter Converter

Python Function Introduction and an Inch-Centimeter Converter#

This example notebook is to illustrate how to create functions in Python. We will create a simple function that converts inches to centimeters and vice versa, a task you will sometimes need to do when reading journal instructions for figure submission. Matplotlib, and thus Seaborn, use inches for figure size specifications, while many journals ask for figure sizes in centimeters.

def inch_to_cm(inches):
    """Convert inches to centimeters."""
    cm = inches * 2.54
    return cm

def cm_to_inch(cm):
    """Convert centimeters to inches."""
    inches = cm / 2.54
    return inches

Example Usage#

For guidance, Nature’s standard figure sizes are 89 mm wide (single column) and 183 mm wide (double column). The full depth of a Nature page is 247 mm. Figures can also be a column-and-a-half where necessary (120–136 mm).

Source

single_column_cm = 8.9  # in cm
double_column_cm = 18.3  # in cm
page_depth_cm = 24.7  # in cm
col_and_a_half_cm = 13.6  # in cm

single_column_inch = cm_to_inch(single_column_cm) # 3.5 inches
double_column_inch = cm_to_inch(double_column_cm) # 7.2 inches
page_depth_inch = cm_to_inch(page_depth_cm)    # 9.72 inches
col_and_a_half_inch = cm_to_inch(col_and_a_half_cm) # 5.35 inches

# Print the results
print(f"Single column width: {single_column_inch:.2f} inches")
print(f"Double column width: {double_column_inch:.2f} inches")
print(f"Page depth: {page_depth_inch:.2f} inches")
print(f"Column and a half width: {col_and_a_half_inch:.2f} inches")

Single column width: 3.50 inches
Double column width: 7.20 inches
Page depth: 9.72 inches
Column and a half width: 5.35 inches

Typed Function Definitions#

You can also add type hints to the function definitions to specify the expected input and output types

def inch_to_cm(inches: float) -> float:
    """Convert inches to centimeters."""
    cm = inches * 2.54
    return cm

def cm_to_inch(cm: float) -> float:
    """Convert centimeters to inches."""
    inches = cm / 2.54
    return inches
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