如何在python中将多个列表合并为一个列表：numpy.mean()

Question

I have problems with merging lists into a list

The followings are what I have tried

import os,glob
from PIL import Image
from skimage import io
import numpy as np
from statistics import stdev 

path = "/Users/Xin/Desktop/SVM-Image-Classification-master/test"
# Delete images with the low pixel value
for filename in os.listdir(path):
    images = Image.open(os.path.join(path,filename))  
    value = [round(np.mean(images).tolist(),2)]
    print(value)
    print(type(value))
    #if np.mean(images) < 20:
        #os.remove(os.path.join(path, filename))
#print(len(os.listdir(path)))

The output as follows

[12.69]
<class 'list'>
[14.46]
<class 'list'>
[12.25]
<class 'list'>
[9.51]
<class 'list'>
[18.7]
<class 'list'>
[10.0]
<class 'list'>
[18.13]
<class 'list'>
[12.63]
<class 'list'>

What I need is merging the above lists into a list so that I can do sum() function to get a total value

Can anyone give me a help? Thanks

Answer 1

Try following way

from numpy import array
from numpy import sum
sum_list = []
for filename in os.listdir(path):
    images = Image.open(os.path.join(path,filename))  
    value = [round(np.mean(images).tolist(),2)]
    sum_list.append(value)
v = array(sum_list)
return sum(v)

Answer 2

Create a list that will store all of the values, then append to it:

all_values = []
for filename in os.listdir(path):
    images = Image.open(os.path.join(path,filename))  
    value = [round(np.mean(images).tolist(),2)]
    all_values = [*all_values, *value]

print(all_values)