Creating a Custom Proper Case Function in Kapa.ai

Andrew S. · 2025-06-17 00:10:29.036369+00

what is the best way to create the equivalent of PROPER() function for a custom property. I see UPPER and LOWER but nothing to do the capitalized first letter. When I try to use LOWER(RIGHT(x,LEN(x)-1)) to get the remainder of the string (x) to be lower, I get an error about the "-1" in the formula.

I'm sorry, but based on the knowledge sources provided, Mixpanel's custom property formula language does not currently include a built-in PROPER() function (which capitalizes the first letter of a string and lowercases the rest). The available string functions are UPPER, LOWER, LEFT, RIGHT, MID, and SPLIT, but there is no documented way to capitalize only the first letter of a string using these functions.Additionally, your attempt to use LOWER(RIGHT(x, LEN(x)-1)) is running into an error because, according to the documentation, the formula language does not support arithmetic operations (like LEN(x)-1) directly inside function arguments. The LEN function returns the length, but you cannot subtract 1 from it within the argument list for RIGHT or similar functions as you might in Excel or SQL. The documentation does not mention support for such dynamic argument calculations within function calls Custom Properties: Functions.In summary, there is no supported or documented way to create a PROPER() equivalent in Mixpanel custom properties at this time. If this functionality is important for your use case, you may need to preprocess your data before sending it to Mixpanel or request this feature from Mixpanel support.

kapa.ai is still learning and improving, please let me know how I did by reacting below.

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