使用OpenCV或Matplotlib/Pyplot可视化MNIST数据集

问题描述

我有MNIST数据集，我正在尝试使用pyplot将其可视化.数据集采用cvs格式，其中每一行都是784像素的一幅图像.我想以pyplot或opencv的格式将其可视化为28 * 28图像格式.我正在尝试直接使用:

i have MNIST dataset and i am trying to visualise it using pyplot. The dataset is in cvs format where each row is one image of 784 pixels. i want to visualise it in pyplot or opencv in the 28*28 image format. I am trying directly using :

plt.imshow(X[2:],cmap =plt.cm.gray_r, interpolation = "nearest")

但是我不能正常工作吗?关于如何处理此问题的任何想法.

but i its not working? any ideas on how should i approach this.

推荐答案

假定您具有此格式的CSV文件，该格式是MNIST数据集可用的格式

Assuming you have a CSV file with this format, which is a format the MNIST dataset is available in

label, pixel_1_1, pixel_1_2, ...

在这里，您可以使用Matplotlib然后使用OpenCV在Python中对其进行可视化

Here's how you can visulize it in Python with Matplotlib and then OpenCV

import numpy as np
import csv
import matplotlib.pyplot as plt

with open('mnist_test_10.csv', 'r') as csv_file:
    for data in csv.reader(csv_file):
        # The first column is the label
        label = data[0]

        # The rest of columns are pixels
        pixels = data[1:]

        # Make those columns into a array of 8-bits pixels
        # This array will be of 1D with length 784
        # The pixel intensity values are integers from 0 to 255
        pixels = np.array(pixels, dtype='uint8')

        # Reshape the array into 28 x 28 array (2-dimensional array)
        pixels = pixels.reshape((28, 28))

        # Plot
        plt.title('Label is {label}'.format(label=label))
        plt.imshow(pixels, cmap='gray')
        plt.show()

        break # This stops the loop, I just want to see one

您可以从上方获取pixels numpy数组，该数组为dtype='uint8'(无符号8位整数)，形状为28 x 28，并使用cv2.imshow()

You can take the pixels numpy array from above which is of dtype='uint8' (unsigned 8-bits integer) and shape 28 x 28 , and plot with cv2.imshow()

    title = 'Label is {label}'.format(label=label)

    cv2.imshow(title, pixels)
    cv2.waitKey(0)
    cv2.destroyAllWindows()

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