Improve melt error message for invalid measure.vars (#6512)#7549
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ayushsingh9720 wants to merge 10 commits intoRdatatable:masterfrom
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Improve melt error message for invalid measure.vars (#6512)#7549ayushsingh9720 wants to merge 10 commits intoRdatatable:masterfrom
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Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## master #7549 +/- ##
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Coverage 98.96% 98.96%
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Files 87 87
Lines 16734 16741 +7
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+ Hits 16560 16567 +7
Misses 174 174 ☔ View full report in Codecov by Sentry. 🚀 New features to boost your workflow:
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ben-schwen
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ben-schwen
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Good start. Case for list(measure.vars) is definitely missing.
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Jan 7, 2026
| @@ -1,3 +1,4 @@ | |||
| if (getRversion() >= "2.15.1") utils::globalVariables(c("n_read")) | |||
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| melt(DT, id.vars=patterns("[in]"), measure.vars=patterns("^f_", "^d_"), value.factor=TRUE) | ||
| # same as above, but provide list of columns directly by column names or indices | ||
| melt(DT, id.vars=1:2, measure.vars=list(3:4, c("d_1", "d_2")), value.factor=TRUE) | ||
| try(melt(DT, id.vars=1:2, measure.vars=list(3:4, c("d_1", "d_2")), value.factor=TRUE)) |
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Summary
This Pull Request addresses issue #6512 by making the error message in
melt.data.tablemore informative when a user provides column names inmeasure.varsthat do not exist in the dataset.Changes
measure.vars. It usessetdiff()to identify exactly which variables are missing from the data and reports them specifically.Impact
Instead of a generic:
Error: One or more values in 'measure.vars' is invalid.Users will now see:
Error: One or more values in 'measure.vars' is invalid; please fix by removing [z1]This change improves the developer experience by pinpointing the exact typo or missing column in the function call.
Closes #6512