plotly / plotly/plotly.R

issue: position_dodge alters hover values

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bug ggplotly
Dominant language
R
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Description

Problem: using position_dodge in at least geom_point seems to incorrectly assign the group values shown when hovering on a point. This is related to whether or not the values in the plot x-axis factor are alphabetically ordered.

Example:

library(ggplot2)
library(plotly)

#Data with x-axis factor in alphabetical order (a, b, c):
data <- data.frame('Col1' = c('a', 'b', 'c'), 'Col2'= factor(1:3), Col3 = c('A1', 'A2', 'A3'), 'Val' = c(10,5,1))
#Hovering on plot dots gives correct values, regardless of position_dodge.
ggplotly(ggplot(data, aes(x = Col1, y = Val, group = Col2:Col3)) + geom_point())
ggplotly(ggplot(data, aes(x = Col1, y = Val, group = Col2:Col3)) + geom_point(position = position_dodge(0.6)))

#Data with x-axis factor in non alphabetical order (c, a, b):
data1 <- data.frame('Col1' = c('c', 'a', 'b'), 'Col2'= factor(1:3), Col3 = c('A1', 'A2', 'A3'), 'Val' = c(10,5,1))
#Hovering on plot dots gives correct values if no position_dodge is used:
ggplotly(ggplot(data1, aes(x = Col1, y = Val, group = Col2:Col3)) + geom_point())
#Hovering on plot dots gives incorrect values (as if the x-axis levels had been reordered?) if position_dodge is used:
ggplotly(ggplot(data1, aes(x = Col1, y = Val, group = Col2:Col3)) + geom_point(position = position_dodge(0.6)))

Both solution and temporary workaround are appreciated. Plotly is superb, thank you so much for putting your time on it.

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First steps

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  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by running the two ggplotly examples using geom_point and position_dodge, comparing the alphabetical and non-alphabetical Col1 cases. Trace how ggplotly transfers grouped point data into hover values; done means the displayed group values remain matched to the correct points when position_dodge is used.

Written by the indexing model from the issue text.

Assessment

Tech stack
r
Domain
data-visualization
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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