I would naturally do it in Emacs Lisp for its superior excel reading abilities (require 'csv-mode) (let ((input-file "bigfile.xls") (out

I would naturally do it in Emacs Lisp for its superior excel reading abilities (require 'csv-mode) (let ((input-file "bigfile.xls") (output-dir "chunked/") (chunksize 1000)) (cl-labels ((read-csv-file (filename) (with-temp-buffer (insert-file-contents filename) (csv-mode) (csv-parse-buffer t))) (write-csv-file (filename data) (with-temp-buffer (csv-mode) (dolist (row data) (csv-insert-list row)) (write-region (point-min) (point-max) filename))) (chunk-data (data chunk-size) (let (result) (while data (push (cl-subseq data 0 (min chunk-size (length data))) result) (setq data (nthcdr chunk-size data))) (nreverse result)))) (let* ((data (read-csv-file input-file)) (chunks (chunk-data data chunk-size)) (file-count 1)) (dolist (chunk chunks) (let ((output-file (expand-file-name (format "chunk-%04d.csv" file-count) output-dir))) (write-csv-file output-file chunk) (setq file-count (1+ file-count)))) (message "Processing complete. %d files created." (1- file-count))))) (This is a joke. Do not use this.)