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07e991d553
* ci(pre-commit): Add pep8-naming to `pre-commit` hooks (#7038) * refactor: Fix naming conventions (#7038) * Update arithmetic_analysis/lu_decomposition.py Co-authored-by: Christian Clauss <cclauss@me.com> * [pre-commit.ci] auto fixes from pre-commit.com hooks for more information, see https://pre-commit.ci * refactor(lu_decomposition): Replace `NDArray` with `ArrayLike` (#7038) * chore: Fix naming conventions in doctests (#7038) * fix: Temporarily disable project euler problem 104 (#7069) * chore: Fix naming conventions in doctests (#7038) Co-authored-by: Christian Clauss <cclauss@me.com> Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
94 lines
2.8 KiB
Python
94 lines
2.8 KiB
Python
"""
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Output:
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Enter an Infix Equation = a + b ^c
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Symbol | Stack | Postfix
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----------------------------
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c | | c
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^ | ^ | c
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b | ^ | cb
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+ | + | cb^
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a | + | cb^a
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| | cb^a+
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a+b^c (Infix) -> +a^bc (Prefix)
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"""
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def infix_2_postfix(infix):
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stack = []
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post_fix = []
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priority = {
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"^": 3,
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"*": 2,
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"/": 2,
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"%": 2,
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"+": 1,
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"-": 1,
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} # Priority of each operator
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print_width = len(infix) if (len(infix) > 7) else 7
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# Print table header for output
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print(
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"Symbol".center(8),
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"Stack".center(print_width),
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"Postfix".center(print_width),
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sep=" | ",
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)
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print("-" * (print_width * 3 + 7))
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for x in infix:
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if x.isalpha() or x.isdigit():
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post_fix.append(x) # if x is Alphabet / Digit, add it to Postfix
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elif x == "(":
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stack.append(x) # if x is "(" push to Stack
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elif x == ")": # if x is ")" pop stack until "(" is encountered
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while stack[-1] != "(":
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post_fix.append(stack.pop()) # Pop stack & add the content to Postfix
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stack.pop()
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else:
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if len(stack) == 0:
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stack.append(x) # If stack is empty, push x to stack
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else: # while priority of x is not > priority of element in the stack
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while len(stack) > 0 and priority[x] <= priority[stack[-1]]:
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post_fix.append(stack.pop()) # pop stack & add to Postfix
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stack.append(x) # push x to stack
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print(
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x.center(8),
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("".join(stack)).ljust(print_width),
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("".join(post_fix)).ljust(print_width),
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sep=" | ",
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) # Output in tabular format
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while len(stack) > 0: # while stack is not empty
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post_fix.append(stack.pop()) # pop stack & add to Postfix
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print(
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" ".center(8),
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("".join(stack)).ljust(print_width),
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("".join(post_fix)).ljust(print_width),
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sep=" | ",
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) # Output in tabular format
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return "".join(post_fix) # return Postfix as str
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def infix_2_prefix(infix):
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infix = list(infix[::-1]) # reverse the infix equation
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for i in range(len(infix)):
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if infix[i] == "(":
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infix[i] = ")" # change "(" to ")"
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elif infix[i] == ")":
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infix[i] = "(" # change ")" to "("
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return (infix_2_postfix("".join(infix)))[
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::-1
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] # call infix_2_postfix on Infix, return reverse of Postfix
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if __name__ == "__main__":
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Infix = input("\nEnter an Infix Equation = ") # Input an Infix equation
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Infix = "".join(Infix.split()) # Remove spaces from the input
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print("\n\t", Infix, "(Infix) -> ", infix_2_prefix(Infix), "(Prefix)")
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