Hey there! Let's break down why you're hitting that IndexError on the hn.append(row[1]) line and get it sorted out.

What's Causing the Error? #

The IndexError: list index out of range message tells us that at least one row in your vert.csv file doesn't have enough values. Specifically, when the code tries to grab row[1] (the second value in the row), that row has fewer than 2 elements total. This usually happens for one of these reasons:

• There's an empty row in your CSV (like a blank line at the end or middle of the file)
• A row has incomplete data (fewer than 3 columns, maybe a missing comma or value)
• The CSV uses a delimiter other than commas (like tabs) and the reader isn't parsing it correctly

Step 1: Debug to Find the Problem Row #

First, let's modify your code to print every row as it's read—this will show you exactly which row is causing the crash. Update your loop like this:

with open("vert.csv") as csvDataFile:
    csvReader = csv.reader(csvDataFile)
    for idx, row in enumerate(csvReader):
        print(f"Processing row {idx}: {row}")  # Print each row to spot issues
        try:
            lr.append(row[0])
            hn.append(row[1])
            ac.append(row[2])
        except IndexError:
            print(f"⚠️ Skipping invalid row {idx}: Only has {len(row)} columns (needs 3)")

Run this, and you'll see exactly which row is missing data. Empty rows will show up as [], and incomplete rows will have fewer than 3 entries.

Step 2: Fix the Issue #

Once you've identified the problem row, you have two straightforward fixes:

1. Edit the CSV file: Open vert.csv and remove any empty rows, fill in missing values, or make sure all rows use commas as separators.
2. Keep the error handling: If you can't modify the CSV, leave the try-except block in place to skip bad rows instead of crashing.

Bonus: Use csv.DictReader for Cleaner, Safer Code (If You Have Headers) #

If your CSV has a header row (like the first line is LR,HN,Performance), switching to DictReader makes your code more readable and less prone to index errors. Here's how to adjust it:

with open("vert.csv") as csvDataFile:
    # Replace the fieldnames with your actual CSV header labels
    csvReader = csv.DictReader(csvDataFile, fieldnames=["lr", "hn", "ac"])
    next(csvReader)  # Skip the header row if you defined fieldnames manually
    for row in csvReader:
        # Access values by column name instead of index
        lr.append(row["lr"])
        hn.append(row["hn"])
        ac.append(row["ac"])

This way, you don't have to worry about column order, and any missing columns will trigger a clear KeyError instead of a vague index error.

Final Check #

After fixing the row issue, your original plotting code should work as expected. Just double-check that your lr, hn, and ac lists are the same length before converting them to numpy arrays!

内容的提问来源于stack exchange，提问作者Courtney Stack