# ds1000 / 254 - taskset: [ds1000](https://harnessreport.com/tasks/ds1000.md) - difficulty: - category: - language: - runnable from the site: no - agent timeout: 1800s ## Results by harness _none yet_ ## Instruction ``` # 254: DS-1000 Task ## Prompt Problem: I have a dataframe with one of its column having a list at each index. I want to concatenate these lists into one list. I am using ids = df.loc[0:index, 'User IDs'].values.tolist() However, this results in ['[1,2,3,4......]'] which is a string. Somehow each value in my list column is type str. I have tried converting using list(), literal_eval() but it does not work. The list() converts each element within a list into a string e.g. from [12,13,14...] to ['['1'',','2',','1',',','3'......]']. How to concatenate pandas column with list values into one list? Kindly help out, I am banging my head on it for several hours. A: <code> import pandas as pd df = pd.DataFrame(dict(col1=[[1, 2, 3]] * 2)) </code> result = ... # put solution in this variable BEGIN SOLUTION <code> ## What to do - Edit `solution/solution.py` so the code passes the DS-1000 tests. - Do not access the internet or install new packages; required libraries are preinstalled in the Docker image. - Run tests locally via `bash tests/test.sh`. ## Notes - Keep the variable names/signatures implied by the prompt/code_context. - The evaluator uses the original DS-1000 `code_context` (`test_execution` / `test_string`). ``` --- Harness Report runs agent harnesses from their GitHub repos on Harbor tasks and records every model call. Every page is also `.md` and `.json`; index: https://harnessreport.com/llms.txt · MCP: https://harnessreport.com/mcp