Creating a nested list using insert() in Python-CodePudding

I'm trying to find a way to create a nested list out of an already-existing non-empty list using built-in list fuctions.

Here is a small example: a=['Groceries', 'School Fees', 'Medicines', 'Furniture'] When I try a[0].insert(0, 1000) for example, I'm met with an error. Is there any way to do this?

CodePudding user response：

You can use indexing to access the first sublist and then use the list.insert() method to insert the new value at the specified index. For example:

a = ['Groceries', 'School Fees', 'Medicines', 'Furniture']
b = [[element] for element in a]

# Add the value 1000 to the first element of the first sublist
b[0].insert(0, 1000)

# The resulting nested list should be: [[1000, 'Groceries'], ['School Fees'], ['Medicines'], ['Furniture']]
print(b)

CodePudding user response：

Make a function for inner inserting.

Try this

a=['Groceries', 'School Fees', 'Medicines', 'Furniture']
def innerInsert(index, value):
    try:
        a[index].insert(index, value)
    except AttributeError:
        a[index] = []
        a[index].insert(index, value)

innerInsert(0, 10000)
innerInsert(0, 100)
print(a)

[[100, 10000], 'School Fees', 'Medicines', 'Furniture']

For more options, I made some changes to the function

a=['Groceries', 'School Fees', 'Medicines', 'Furniture']
def innerInsert(l, iLstIndex, iLstValueIndex, value):
    try:
        l[iLstIndex].insert(iLstValueIndex, value)
    except AttributeError:
        l[iLstIndex] = []
        l[iLstIndex].insert(iLstValueIndex, value)

innerInsert(a, 0, 0, 10000)
innerInsert(a, 0, 1, 2)
innerInsert(a, 0, 2, 3)
innerInsert(a, 0, 3, 4)
innerInsert(a, 0, 4, 1)
innerInsert(a, 0, 5, 2)
innerInsert(a[0], 4, 2, 100)
print(a)

OUTPUT

[[10000, 2, 3, 4, [100], 2], 'School Fees', 'Medicines', 'Furniture']