python - Matplotlib graphic image to base64

Question

Problem : Need to transform a graphic image of matplotlib to a base64 image

Current Solution : Save the matplot image in a cache folder and read it with read() method and then convert to base64

New Problem : Annoyance : Need a workaround so I dont need to save the graphic as image in any folder. I want to just use the image in the memory. Doing unnecessary I/O is a bad practice.

def save_single_graphic_data(data, y_label="Loss", x_label="Epochs", save_as="data.png"):
    total_epochs = len(data)
    plt.figure()
    plt.clf()

    plt.plot(total_epochs, data)

    ax = plt.gca()
    ax.ticklabel_format(useOffset=False)

    plt.ylabel(y_label)
    plt.xlabel(x_label)

    if save_as is not None:
        plt.savefig(save_as)

    plt.savefig("cache/cached1.png")

    cached_img = open("cache/cached1.png")

    cached_img_b64 = base64.b64encode(cached_img.read())

    os.remove("cache/cached1.png")

    return cached_img_b64

Answer 1

import cStringIO
my_stringIObytes = cStringIO.StringIO()
plt.savefig(my_stringIObytes, format='jpg')
my_stringIObytes.seek(0)
my_base64_jpgData = base64.b64encode(my_stringIObytes.read())

[edit] in python3 it should be

import io
my_stringIObytes = io.BytesIO()
plt.savefig(my_stringIObytes, format='jpg')
my_stringIObytes.seek(0)
my_base64_jpgData = base64.b64encode(my_stringIObytes.read())

I think at least ... based on the documentation http://matplotlib.org/api/pyplot_api.html#matplotlib.pyplot.savefig