how to remove specific char from array in python

Question

img = cv2.imread('img/dream.jpg')
(b,g,r)=cv2.split(img)
color = ('b','g','r')
b = cv2.calcHist([img],[0],None,[256],[0, 256])
g = cv2.calcHist([img],[1],None,[256],[0, 256])
r = cv2.calcHist([img],[2],None,[256],[0, 256])
     
for i, col in enumerate(color):
    histr = cv2.calcHist([img],[i],None,[256],[0, 256])
    plt.plot(histr, color = col)
    plt.xlim([0, 256])   
    
with open('output.csv', 'w', newline='') as csvfile:
    writer = csv.writer(csvfile)
    writer.writerow('BGR')
    for row in rows:
        writer.writerow(row)

I am trying to read in a picture and show its RGB counts of each pixel. It's all cool until I tried to write my data into a csv file. Here is what it look like:

B,G,R
[0.],[0.],[631788.]
[0.],[0.],[418355.]
[0.],[0.],[105815.]

All I need is to remove the '[' and ']' from my array.

I am new to python I am not sure whether the array is tuple dictionary or something else.

I have tried the replace() method however it appear an error message 'numpy.ndarray' object has no attribute 'replace'

To discover the type of the object, you can use the type(obj). — Daniel Labbe
– Daniel Labbe, Commented Feb 21, 2019 at 15:44
Please update your question with a small amount of text of the csv file, rather than a link to an image. — quamrana
– quamrana, Commented Feb 21, 2019 at 15:45

Teghan Nightengale · Accepted Answer · 2019-02-21 16:19:15Z

1

Every value in your array is within its own list. In python you access elements of a list using an index.

In your case, you can convert your array of lists (with each list having only one value i[0]) using the following:

delisted_array = np.array([i[0] for i in your_array_of_lists])

This list comprehension says: "take the value from first index of each (list) found in this array and put those values in a list".

Eg.

In [70]: a = np.array([[1],[2]])

In [71]: a
Out[71]: 
array([[1],
       [2]])

In [72]: delisted_array = np.array([i[0] for i in a])

In [73]: delisted_array
Out[73]: array([1, 2])

edited Feb 21, 2019 at 16:19

answered Feb 21, 2019 at 16:14

Teghan Nightengale

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mooga · Accepted Answer · 2019-02-21 16:17:15Z

1

What you need is to convert a list to String by

list_string = ''.join(list_name)

as well if you have a matrix

you will need

for item in list_outer:
  item = ''.join(item)

list_outer = ''.join(list_outer)

edited Feb 21, 2019 at 16:17

answered Feb 21, 2019 at 15:46

mooga

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9 Comments

Paga Over a year ago

i have converted it to list but still appears error could you explain it more clearly thanks for your reply

mooga Over a year ago

you mean convert it to string , what error you have ?

Paga Over a year ago

imgur.com/a/0Yhcx91 this is what happen when i convert it to string and do the same implement as i did above

mooga Over a year ago

could you update the code with where exactly you convert the list to string , and which one

mooga Over a year ago

@Paga, i have update the answer , if you have a matrix

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