Solve OSError: cannot open resource self.font = core.getfont(font, size, index, encoding, layout_engin

Solve OSError: cannot open resource self.font = core.getfont(font, size, index, encoding, layout_engin

When programming in Python, we sometimes encounter the error??OSError: cannot open resource self.font = core.getfont(font, size, index, encoding, layout_engin??. This error is usually It is caused by missing font files or incorrect font file paths. This article will explain how to solve this error.

Problem description

When we use certain graphics libraries (such as Matplotlib, Pillow, etc.) in Python programs, we may encounter??OSError: cannot open resource self.font = core.getfont(font, size, index, encoding , layout_engin??This error. This error prompts that the font resource cannot be opened.

Solution

Method 1: Install font files

Usually, we can solve the problem by installing the missing font files.

  1. First, identify the font files you need. You can download the required font files from the official font library, or obtain suitable font files from other sources.
  2. Copy the font files to your operating system’s fonts directory. In Windows operating systems, the font directory is usually located at ??C:\Windows\Fonts??; in Linux systems, the font files can be copied to ??/usr/share /fonts?? or ?~/.fonts?? directory.
  3. Rerun the program and check whether the ??OSError?? error still occurs.

Method 2: Specify font path

If you cannot install the font file directly into the operating system’s font directory, or the font file is located in a non-standard path, you can also solve the problem by specifying the path to the font file. Before using the relevant graphics library, you can use the following code to specify the font file path:

pythonCopy codeimport matplotlib.pyplot as plt
import matplotlib.font_manager as fm
#Specify font file path
font_path = "/path/to/your/font.ttf"
# Register font
fm.fontManager.addfont(font_path)
# Set default font
plt.rcParams["font.family"] = fm.FontProperties(fname=font_path).get_name()
#Run your code
# ...

Replace ??/path/to/your/font.ttf?? with your actual font file path. This way, the program will use the font file at the specified path.

Summary

??OSError: cannot open resource self.font = core.getfont(font, size, index, encoding, layout_engin?? The error is usually caused by a missing font file or an incorrect font file path. By installing Missing font file or specify the path of the font file, we can solve this problem. Hope the solutions in this article can help you solve the ??OSError?? error. If you have any questions or queries, please feel free to message.

Suppose you are using Matplotlib to draw a chart and save it as an image, but during the saving process, you encounter ??OSError: cannot open resource self.font = core.getfont(font, size, index, encoding, layout_engin?? error. At this time we can use the method of specifying the font path to solve this problem. Here is a sample code:

pythonCopy codeimport matplotlib.pyplot as plt
import matplotlib.font_manager as fm
#Specify font file path
font_path = "/path/to/your/font.ttf"
# Register font
fm.fontManager.addfont(font_path)
# Set default font
plt.rcParams["font.family"] = fm.FontProperties(fname=font_path).get_name()
# Draw a chart
x = [1, 2, 3, 4, 5]
y = [10, 20, 30, 40, 50]
plt.plot(x, y)
#Save chart as image
plt.savefig("output.png")
# show chart
plt.show()

In the above code, we first specify the path of the font file??font_path??, and then register the font file through??fm.fontManager.addfont??. Next, we use ??plt.rcParams["font.family"]?? to set the default font to the font file in the specified path. Finally, we use Matplotlib to draw the chart, save the chart as an image, and display the chart through??plt.show()??. This way, the ??OSError?? error will no longer appear when saving the chart. Please note to replace ??/path/to/your/font.ttf?? in the sample code with the actual font file path to ensure that the font file exists and is correct.

Fonts in Matplotlib

In Matplotlib, fonts are a key element used for the style and display of labels, titles, and other text elements. Matplotlib provides multiple ways to set fonts, including global settings and local settings.

Global font settings

By modifying the global font settings, you can uniformly set the font style throughout Matplotlib.

pythonCopy codeimport matplotlib.pyplot as plt
# Set global font
plt.rcParams["font.family"] = "sans-serif"
plt.rcParams["font.sans-serif"] = "Arial"

In the above example, the global font family is set to “sans-serif” (sans serif font) through??plt.rcParams["font.family"]?? Then set the specific font to “Arial” through??plt.rcParams["font.sans-serif"]??.

Local font settings

In addition to global settings, font styles can be set through specific methods or properties of individual Matplotlib objects.

pythonCopy codeimport matplotlib.pyplot as plt
fig, ax = plt.subplots()
#Set title font
ax.set_title("Title", fontfamily="serif", fontsize=14, fontstyle="italic", fontweight="bold")
#Set the X-axis label font
ax.set_xlabel("X Label", fontfamily="sans-serif", fontsize=12, rotation=45)
#Set Y-axis label font
ax.set_ylabel("Y Label", fontfamily="monospace", fontsize=12)
#Set tick font
ax.tick_params(axis="both", labelsize=10, labelfontfamily="fantasy")
plt.show()

In the above example, the font of the title is set through the ??ax.set_title()?? method. You can specify the font family, font size, font style and font weight. Similarly, the font of the X-axis and Y-axis labels can be set through the ??ax.set_xlabel()?? and ??ax.set_ylabel()?? methods, and The ??ax.tick_params()?? method can set the font style of the tick.

Fonts in Pillow

Pillow is a powerful Python image processing library that also involves font processing.

Load font

In Pillow, we can use the ??ImageFont?? module to load and use font files.

pythonCopy codefrom PIL import Image, ImageDraw, ImageFont
#Load font file
font = ImageFont.truetype('/path/to/font.ttf', size=18)

In the above example, we use the ??ImageFont.truetype()?? method to load the font file at the specified path and specify the font size as 18.

Draw text on image

After loading the font, we can use the ??ImageDraw?? module to draw text on the image.

pythonCopy codefrom PIL import Image, ImageDraw, ImageFont
image = Image.new('RGB', (200, 200), (255, 255, 255))
draw = ImageDraw.Draw(image)
#Set the font for drawing text
font = ImageFont.truetype('/path/to/font.ttf', size=18)
# draw text
text = "Hello, World!"
draw.text((50, 50), text, fill=(0, 0, 0), font=font)
image.show()

In the above code, we first create a new image object??image??, and then create a new image object that can be used in the image through the??ImageDraw.Draw()?? method The object drawn on??draw??. Next, we set the font for drawing text, which is the font object loaded above. Finally, use the draw.text() method to draw the specified text on the image and specify the fill color and font. Through the above introduction, I hope you have a more detailed understanding of fonts in Matplotlib and Pillow. They provide a wealth of font settings and operation options to meet different needs, making charts and images more beautiful and professional.

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