Do not open files larger than 100MB in Excel; it will truncate data.
Use head -n 20 406K.txt to preview the first 20 lines without loading the whole file. 📊 Data Analysis Guide 406K.txt
If it’s a list of 406,000 IDs, you likely need to filter it against a master phenotype file using df.merge() . 🔬 Contextual Use Cases Do not open files larger than 100MB in