Summing CSV Rows

Python
import pandas as pd

def add_totals_row(input_path, output_path=None, label_col=None):
    df = pd.read_csv(input_path)
    output_path = output_path or input_path

    totals = {}
    for col in df.columns:
        if pd.api.types.is_numeric_dtype(df[col]):
            totals[col] = df[col].sum()
        else:
            totals[col] = ""

    # Put a "Total" label in the first non-numeric column (or specified label_col)
    label_target = label_col or next(
        (c for c in df.columns if not pd.api.types.is_numeric_dtype(df[c])), df.columns[0]
    )
    totals[label_target] = "Total"

    df_out = pd.concat([df, pd.DataFrame([totals])], ignore_index=True)
    df_out.to_csv(output_path, index=False)
    return df_out

add_totals_row("data.csv", "data_with_totals.csv")

For Excel files with multiple sheets:

Python
def add_totals_to_all_sheets(input_path, output_path):
    sheets = pd.read_excel(input_path, sheet_name=None)
    with pd.ExcelWriter(output_path, engine="openpyxl") as writer:
        for name, df in sheets.items():
            totals = {
                col: df[col].sum() if pd.api.types.is_numeric_dtype(df[col]) else ""
                for col in df.columns
            }
            label_col = next(
                (c for c in df.columns if not pd.api.types.is_numeric_dtype(df[c])), df.columns[0]
            )
            totals[label_col] = "Total"
            df_out = pd.concat([df, pd.DataFrame([totals])], ignore_index=True)
            df_out.to_excel(writer, sheet_name=name, index=False)

Progress:

• Identify input format (single CSV, multi-sheet Excel, or folder of CSVs)
• Load each sheet/file into a DataFrame
• Detect numeric columns automatically (don't hardcode column names)
• Compute column sums, skip/blank non-numeric columns
• Insert a clear label ("Total", "Sum", or "TOTAL") in the leftmost text column
• Append totals as the final row, preserving original column order
• Write output (overwrite or new file, per user preference)
• Verify row/column counts: output rows = input rows + 1

Example 1: Input (sales.csv):

Region,Q1,Q2,Q3
East,100,150,200
West,80,90,110

Output (sales.csv):

Region,Q1,Q2,Q3
East,100,150,200
West,80,90,110
Total,180,240,310

Example 2: Input: Excel workbook with sheets "Jan" and "Feb", each with a Date, Amount, Units columns. Output: Same workbook, each sheet gets a final row Total,,<sum_amount>,<sum_units> (Date left blank since it's non-numeric but not the label column).

Example 3: Input: Folder of 5 CSVs with identical schema. Output: Each CSV processed independently, each gets its own totals row — no cross-file aggregation unless explicitly requested.