CODEWITHSUNDEEP
pythonnested-lists
Guriqbal Chouhan
Guriqbal Chouhan

Reputation: 49

Adding lists to a new list

I did not get this question right. The function read_words turns a text file with a bunch of names in new lines into a list and it works.

def read_words(words_file):
    """ (file open for reading) -> list of str
    Return a list of all words (with newlines removed) from open file
    words_file.
    Precondition: Each line of the file contains a word in uppercase characters
    from the standard English alphabet.
    """
    words_list = []
    words = words_file.readlines()
    for i in range(len(words)):
        new_word = words[i]
        for char in '\n':
            new_word = new_word.replace(char,'')
            words_list.append(new_word)
    return words_list

the problem arises when I try to get a list of lists

def read_board(board_file):
    """ (file open for reading) -> list of list of str
    Return a board read from open file board_file. The board file will contain
    one row of the board per line. Newlines are not included in the board.
    """
    board_list = []
    row_list = []
    rows = read_words(board_file)
    for i in range(len(rows)):
        for  char in rows[i]:
            row_list.append(char)
        board_list.append(row_list)
    return board_list

the goal is to turn a text file of the type:

ABCD
EFGH

into [['A','B','C','D'],['E','F','G','H']]

I have already tried playing around with the indices for board_list.append(row_list) call without luck. How can I get this to work?

Upvotes: 2

Views: 191

Answers (1)

Stephen Rauch
Stephen Rauch

Reputation: 49862

You can do that with a list comprehension and .strip() like:

Code:

def read_board(board_file):
    return [list(line.strip()) for line in read_words(board_file)]

Test Code:

def read_words(words_file):
    """ (file open for reading) -> list of str
    Return a list of all words (with newlines removed) from open file
    words_file.
    Precondition: Each line of the file contains a word in uppercase characters
    from the standard English alphabet.
    """
    return [word.strip() for word in words_file.readlines()]

def read_board(board_file):
    """ (file open for reading) -> list of list of str
    Return a board read from open file board_file. The board file will contain
    one row of the board per line. Newlines are not included in the board.
    """
    return [list(line) for line in read_words(board_file)]

with open('file1', 'rU') as f:
    board = read_board(f)

print(board)

Results:

[['A', 'B', 'C', 'D'], ['E', 'F', 'G', 'H']]

Upvotes: 3

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