Update values in a column while looping over through a pandas dataframe

Question

I am working on a script to extract some details from images. I am trying to loop over a dataframe that has my image names. How can I add a new column to the dataframe, that populates the extracted name appropriately against the image name?

for image in df['images']:
    concatenated_name                    = ''.join(name)
    df.loc[image, df['images']]['names'] = concatenated_name

Expected:

Index images names
0     img_01 TonyStark
1     img_02 Thanos
2     img_03 Thor

Got:

Index images names
0     img_01 Thor
1     img_02 Thor
2     img_03 Thor

Answer 1

Use apply to apply a function on each row:

def get_name(image):
    # Code for getting the name
    return name

df['names'] = df['images'].apply(get_name)

---

Follwing your answer that added some more details, it should be possible to shorten it to:

def get_details(filename):
    image = os.getcwd() + filename
    data = pytesseract.image_to_string(Image.open(image))
    .
    .
    . 
    data = ''.join(a) 
    return data

df['data'] = df['filenames'].apply(get_details)
# save df to csv / excel / other

Answer 2

After multiple trials, I think I have a viable solution to this question.

I was using nested function for this exercise, such that function 1 loops over a dataframe of files and calls to function 2 to extract text, perform validation and return a value if the image had the expected field. First, I created an empty list which would be populated during each run of function 2. At the end, the user can choose to use this list to create a dataframe.

# dataframes to store data
df = pd.DataFrame(os.listdir(), columns=['filenames'])
df = df[df['filenames'].str.contains(".png|.jpg|.jpeg")]
df['filenames'] = '\\' + df['filenames']
df1 = [] #Empty list to record details 

# Function 1
def extract_details(df):
    for filename in df['filenames']:
        get_details(filename)

# Function 2
def get_details(filename):
    image = os.getcwd() + filename
    data = pytesseract.image_to_string(Image.open(image))
    .
    .
    . 
    data = ''.join(a) 
    print(filename, data)
    df1.append([filename, data])

df_data = pd.DataFrame(df1, columns=['filenames', 'data']) # Container for final  output
df_data.to_csv('data_list.csv') # Write output to a csv file 
df_data.to_excel('data_list.xlsx') # Write output to an excel file