How Can I Fill The Remainder Of The First Column Of An N X N Matrix With 1's, Once A Certain Condition Is Met In My For Loop?

I have an N x N matrix filled with 0's as follows: str1 = 'Patrick' str2 = 'Garrick' matrix = [[0 for _ in range(len(str1))] for _ in range(len(str2))] I am iterating over the fi

Solution 1:

The pure python answer is that you need to iterate:

flag = 0for i in range(len(str2)):
    if str2[i] == str1[0]:
        flag = 1
    matrix[i][0] = flag

You can make it simpler by finding the index up front since your matrix is already zeros:

try:
    i = str2.find(str1[9])
except:
    passelse:
    for j inrange(i, len(str2)):
        matrix[j][0] = 1

You can cheat for the first column (won't work for the rest):

try:
    i = str2.find(str1[9])
except:
    passelse:
    matrix[i:] = [1] + [0for _ inrange(len(str1) - 1)]

If you're willing to use numpy, you can do this without looping explicitly, delegating instead to under-the-hood vectorized loops:

s1 = np.array(list(str1))
s2 = np.array(list(str2))
matrix = np.maximum.accumulate(s2[:, None] == s1, axis=0)

Solution 2:

I think this does what you want. Note I'm using different strings as input so the conditional will be be met (several times).

from pprint import pprint

str1 = "Patrick"
str2 = "GaPPicP"

matrix = [[0for _ inrange(len(str1))] for _ inrange(len(str2))]

for i inrange(len(str2)):
    if str2[i] == str1[0]:   # this is the condition!for j inrange(len(str2)):
            matrix[j][i] = 1

pprint(matrix)

Output:

[[0, 0, 1, 1, 0, 0, 1],
 [0, 0, 1, 1, 0, 0, 1],
 [0, 0, 1, 1, 0, 0, 1],
 [0, 0, 1, 1, 0, 0, 1],
 [0, 0, 1, 1, 0, 0, 1],
 [0, 0, 1, 1, 0, 0, 1],
 [0, 0, 1, 1, 0, 0, 1]]

Solution 3:

You just need to loop through range(i, len(str2)) and assign 1 to matrix[j][0].

Demo:

str1 = "Patrick"
str2 = "Garrick"

matrix = [[0for _ inrange(len(str1))] for _ inrange(len(str2))]
print(matrix)

for i inrange(len(str2)):
    if str2[i] == str1[0]:  # this is the condition!for j inrange(i, len(str2)):
            matrix[j][0] = 1breakelse:
        matrix[i][0] = 0print(matrix)

Note: For the given strings, your condition will never become True. You can test it some other values e.g. with str1 = "aatrick".