Category: Python Answers

Sometimes, we want to create a copy of an object in Python.

In this article, we’ll look at how to create a copy of an object in Python.

How to create a copy of an object in Python?

To create a copy of an object in Python, we can use the copy.copy method to create a shallow copy of an object.

We can use copy.deepcopy to create a deep copy of an object.

For instance, we write

import copy

class C():
    def __init__(self):
        self.x = [1]
        self.y = [2]

c = C()
d = copy.copy(c)

to create a shallow copy of object c and assign it to d.

Likewise, we write

d = copy.deepcopy(c)

to create a deep copy of object c and assign it to d.

Conclusion

To create a copy of an object in Python, we can use the copy.copy method to create a shallow copy of an object.

We can use copy.deepcopy to create a deep copy of an object.

Sometimes, we want to use pytesseract OCR to recognize text from an image with Python.

In this article, we’ll look at how to use pytesseract OCR to recognize text from an image with Python.

How to use pytesseract OCR to recognize text from an image with Python?

To use pytesseract OCR to recognize text from an image with Python, we call the image_to_string function.

For instance, we write

import pytesseract
from PIL import Image

text = pytesseract.image_to_string(Image.open("temp.jpg"), lang='eng',
                        config='--psm 10 --oem 3 -c tessedit_char_whitelist=0123456789')

print(text)

to open the image with PIL’s Image.open method.

Then we call image_tp_string with the --psm flag to read the image in as a string.

The string would have the characters in the opened image.

Conclusion

To use pytesseract OCR to recognize text from an image with Python, we call the image_to_string function.

Sometimes, we want to find the max of two or more columns with Python Pandas.

In this article, we’ll look at how to find the max of two or more columns with Python Pandas.

How to find the max of two or more columns with Python Pandas?

To find the max of two or more columns with Python Pandas, w ecan use the max method.

For instance, we write

df["C"] = df[["A", "B"]].max(axis=1)

to add column C to the df data frame by getting a data frame from with df‘s columns A and B with df[["A", "B"]] and call max on it.

We set axis to 1 to getc the max of the value in the row between the 2 columns.

Conclusion

To find the max of two or more columns with Python Pandas, w ecan use the max method.

Sometimes, we want to override save for model with Python Django.

In this article, we’ll look at how to override save for model with Python Django.

How to override save for model with Python Django?

To override save for model with Python Django, we add our own save method to the model class.

For instance, we write

class Model(model.Model):
    _image=models.ImageField(upload_to='folder')
    thumb=models.ImageField(upload_to='folder')
    description=models.CharField()

    def set_image(self, val):
        self._image = val
        self._image_changed = True

        # Or put whole logic in here
        small = rescale_image(self.image,width=100,height=100)
        self.image_small=SimpleUploadedFile(name,small_pic)

    def get_image(self):
        return self._image

    image = property(get_image, set_image)

    def save(self, *args, **kwargs):
        if getattr(self, '_image_changed', True):
            small=rescale_image(self.image,width=100,height=100)
            self.image_small=SimpleUploadedFile(name,small_pic)
        super(Model, self).save(*args, **kwargs)

to add the save method into the Model class.

In it, we call rescale_image to rescale an image,

Then we create a SimpleUploadedFile object from the image.

And then we call save to save the Model instance with the parent class’ save method.

Conclusion

To override save for model with Python Django, we add our own save method to the model class.

Sometimes, we want to use Python regular expression with Unicode.

In this article, we’ll look at how to use Python regular expression with Unicode.

How to use Python regular expression with Unicode?

To use Python regular expression with Unicode, we can use the re.compile method.

For instance, we write

myre = re.compile(ur'[\u0000\u0000\u0000\u0000\u0000\u0000]+', 
                      re.UNICODE)

to call re.compile with the Unicode regex string ur'[\u0000\u0000\u0000\u0000\u0000\u0000]+'.

The 2nd argument is re.UNICODE so re.compile will treat the first argument as a Unicode regex string.

Conclusion

To use Python regular expression with Unicode, we can use the re.compile method.