How can I substitute a list by index in python?-CodePudding

I need to write a function that contains 3 input parameters:

A list called randome containing random integer numbers
A list called indexes that contains (non-negative) indexes of items that need substitution by the third parameter. It is possible that indexes contains non-existent indexes for source. Check if the index actually exists in source before you substitute. Perhaps using the len of randome?
A value new_value that we use to overwrite the items in source. Assign True as default value.

For example: substitution_function([1, 2, 3, 4, 5], [0, 2], True) must return this list: [True, 2, True, 4, 5]

Anyone have any ideas?

def substitution_function(randome, indexes, new_value=True):

    result = []
    for data in indexes:
        if data <= len(source):
            result.append(new_value)
        else:
            for i in range(len(source)):
                result.append(source[i])    
    return result

But this code can be greatly improved

CodePudding user response：

The way you started is strange, let's start from scratch. There is 2 ways

Replace with the given value, at the given indexes

def substitution_function(source, indexes, new_value=True):
    for index in indexes:
        if index < len(source):
            source[index] = new_value
    return source

Build a whole new list, and conditionally use original value or replacement one

# that solution is safe-proof to invalid index
def substitution_function(source, indexes, new_value=True):
    result = []
    indexes = set(indexes) # can be added in case of large list
    for i, data in enumerate(source):
        if i in indexes:
            result.append(new_value)
        else:
            result.append(data)
    return result

CodePudding user response：

I think it's better to you read the Stack Overflow Guidelines