What does 'i<i or 1>' mean in python?
Question:
I was taking a look at the code and found <> behind the variable. At first I thought it’s the same as [] for indexing, but still cannot figure out the exact purpose of using it.
Anyone would let me know what it is or the keyword for googling it?
Answers:
i<0 is an expression that test if the variable i is strictly less than 0 which in this case means i is negative. Can’t read the 2nd thing but i >= means greater or equal to something.
The line of code in question is obscured by the blue pen, but I assume it is supposed to be this:
if i<0 or i>=len(mat) or j<0 or j>= len(mat[0]):
continue
From your description, it seems as though you think i<0 or i> is one expression, but this is incorrect. In actual fact, the expressions are i<0, i>=len(mat), j<0 and j>= len(mat[0]). To make the precedence of the operators clearer, I have added parentheses and spaces below:
if (i < 0) or (i >= len(mat)) or (j < 0) or (j >= len(mat[0])):
continue
The mat variable is a two-dimensional matrix, indexed by i and j. The code above checks both i and j to see if they are within the bounds of the matrix. In other words, it makes sure that they are not less then zero, and not greater than the highest vertical or horizontal index.
I was taking a look at the code and found <> behind the variable. At first I thought it’s the same as [] for indexing, but still cannot figure out the exact purpose of using it.
Anyone would let me know what it is or the keyword for googling it?
i<0 is an expression that test if the variable i is strictly less than 0 which in this case means i is negative. Can’t read the 2nd thing but i >= means greater or equal to something.
The line of code in question is obscured by the blue pen, but I assume it is supposed to be this:
if i<0 or i>=len(mat) or j<0 or j>= len(mat[0]):
continue
From your description, it seems as though you think i<0 or i> is one expression, but this is incorrect. In actual fact, the expressions are i<0, i>=len(mat), j<0 and j>= len(mat[0]). To make the precedence of the operators clearer, I have added parentheses and spaces below:
if (i < 0) or (i >= len(mat)) or (j < 0) or (j >= len(mat[0])):
continue
The mat variable is a two-dimensional matrix, indexed by i and j. The code above checks both i and j to see if they are within the bounds of the matrix. In other words, it makes sure that they are not less then zero, and not greater than the highest vertical or horizontal index.