Look before you clean
read_file and Shell show the real values in each column before any rule is written. Odd values hide there.
Data cleaning in machine learning comes down to written rules: which values to fix, which rows to drop and which gaps to flag. Fredit Flow turns those rules into a Python script, runs it, saves a new file and shows the diff. You review each step.
read_file and Shell show the real values in each column before any rule is written. Odd values hide there.
write_file saves a Python cleaning script, so the next export gets the same rules instead of new manual edits.
edit_file changes a script and shows the diff; in Ask first mode you accept or refuse it before it is applied.
Split the data into training and test parts before you fit any scaling or median fill, then apply what you calculated on the training part to the test part. Statistics come from training only.
./ratings.csvsample read,, ./ratings.csv6 matches./prepare.pysavedyour Python command prepare.pyexit 0./train_clean.csvgaps filled./test_clean.csvgaps filledData preprocessing in machine learning adds steps after cleaning, such as encoding categories and scaling numbers, and every statistic must come from the training part only. Say you want the missing ages in ratings.csv filled with a median. Fredit Flow uses grep to find lines with empty fields, write_file to save prepare.py and Shell to run it with your own Python command. The script writes train_clean.csv and test_clean.csv, with the median calculated on the training rows and then applied to the test rows. Your ratings.csv stays untouched. In Ask first mode the card pauses before the write, so you read the diff, compare the row counts the script prints and spot-check 5 rows in each new file. A pipeline to clean messy real world data can start as this one script.
Impossible values, such as a negative age or a negative price, hide in large files. If you are spending most of your time cleaning data for ML, write each rule down once and let the script apply it. Handling missing values, duplicates and outliers needs a separate rule for each, written down before the script runs. Fredit Flow uses read_file to check the column names, edit_file to add a range check to the script and Shell to run it, reporting the exit code and a count of rows outside the range. Rows that fail go to a review file. Nothing is deleted. Plan only mode lists these checks first. Read the review file line by line before you change a rule.
Fredit Flow is not a hosted service or a plugin for other software. It is meant only for your own files, your PC and servers you are authorised to use, so keep the work to data you own or have the right to process. You review the results. Nothing here promises that code or cleaning rules are correct.