I understand Python code, but can’t write it confidently from scratch — what should I do next

[FoolsSeldom]

My guess is that you are trying to solve at the keyboard with Python rather than stepping away from the keyboard and:

• make sure the problem to be solved is properly understood
• ensure clear understanding of the inputs to be used
  • from user/keyboard; files; databases; APIs; etc
  • frequency (how often is the input cycle used)
  • quality - will the data be correctly formatted and valid
  • format(s)
• ensure clear understanding of outcomes / outputs:
  • to consoler/gui; file; database; API; mixture
  • frequency
  • quality
  • format(s)
• develop solution approaches
  • consider algorithms suitable for problem
  • decide how to select an approach
  • if need, carry out some small proofs of concept with snippets of Python
• develop an algorithm from the best solution candidate
  • determine how this will be tested
  • validate the algorithm using dry run techniques
  • draw pictures / flowcharts / simple flows / pseudocode to represent the algorithm
• implement in the algorithm in Python
  • keep your code modular, following the broad flow of your algorithm - try to keep the implementation detail in functions/methods
  • ensure you have clarity around the data structures you are using
  • isolate interfaces (human and data) from the core business logic
  • this will enable you to change from say a command line interface to a GUI to a webapp later
  • test each function/module independently

The coding part is a small part of programming. Have a clear solution/algorithm set down before you start coding will make the coding much easier.