Join elements of a nested list based on condition

I have a nested array called element_text in the form of for example:

[[1, 'the'], [1, 'quick brown'], [2, 'fox jumped'], [2, 'over'], [2, 'the'], [3, 'lazy goat']] 

And would like to concatenate the elements in the array and return a new array called page_text as so:

[[1, 'the quick brown'], [2, 'fox jumped over the'], [3, 'lazy goat']]

So, if the first number is the same, join the second text strings together with a space in between.

I’ve tried:

page_text = []

for i in element_text:
    #join the list of strings together if the page number is the same
    if i[0] == i[0]:
        text = " ".join(i[1])
        page_text.append([i[0], text])

But this just returns the same array as what was there in the first place.

Any help appreciated!

Thanks,

Carolina

>Solution :

Solution:

You can use pandas by grouping the records by your number and joining all the strings together into a new column.

import pandas as pd

data = [[1, 'the'], [1, 'quick brown'], [2, 'fox jumped'], [2, 'over'], [2, 'the'], [3, 'lazy goat']] 
df = pd.DataFrame(data, columns=['num','text'])

df['full_text'] = df.groupby(['num'])['text'].transform(lambda x : ' '.join(x))
df = df[['num','full_text']].drop_duplicates(subset='num')

df.head()

#   num full_text
#0  1   the quick brown
#2  2   fox jumped over the
#5  3   lazy goat