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I have some questions about purrr::pmap to make multiple plots of ggplot in nested.data.frame.

I can run below code without problem by using purrr::map2 and I can make multiplots(2 plots) in nested.data.frame.

As a example, I used the iris dataset in R.

library(tidyverse)

iris0 <- iris
iris0 <-
iris0 %>%  
group_by(Species) %>%  
nest() %>%  
mutate(gg1 = purrr::map(data, ~ ggplot(., aes(Sepal.Length, Sepal.Width)) + geom_point())) %>%
mutate(gg2 = purrr::map(data, ~ ggplot(., aes(Sepal.Length, Petal.Width)) + geom_point())) %>%
mutate(g = purrr::map2(gg1, gg2, ~ gridExtra::grid.arrange(.x, .y)))

But, when I want to plot more than 2 plots, I can't solve using purrr::pmap like below code.

iris0 <-  
iris0 %>%  
group_by(Species) %>%  
nest() %>%  
mutate(gg1 = purrr::map(data, ~ ggplot(., aes(Sepal.Length, Sepal.Width)) + geom_point())) %>%
mutate(gg2 = purrr::map(data, ~ ggplot(., aes(Sepal.Length, Petal.Width)) + geom_point())) %>%
mutate(gg3 = purrr::map(data, ~ ggplot(., aes(Sepal.Length, Petal.Length)) + geom_point())) %>%
mutate(g = purrr::pmap(gg1, gg2,gg3, ~ gridExtra::grid.arrange(.x, .y, .z)))

> Error in mutate_impl(.data, dots) : Index 1 is not a length 1 vector

Is there is a way of solving this problem in nested.data.frame ? Please give me some advices or answers.

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Lc_decg
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1 Answers1

25

purrr::pmap takes (at least) two arguments:

 pmap(.l, .f, ...)

where

  .l: A list of lists. The length of '.l' determines the number of
      arguments that '.f' will be called with. List names will be
      used if present.
  .f: A function, formula, or atomic vector.

Further, .x and .y work well for only two arguments, but (in the same man page) it says For more arguments, use '..1', '..2', '..3' etc.

For readability (and a little efficiency), I'll combine all of the individual calls to mutate into one; you can keep them separate if needed (esp if there is more to the code than you show in this reduced example):

library(dplyr)
library(tidyr)
library(purrr)
library(ggplot2)
iris0 <- iris %>%  
  group_by(Species) %>%  
  nest() %>%  
  mutate(
    gg1 = purrr::map(data, ~ ggplot(., aes(Sepal.Length, Sepal.Width)) + geom_point()),
    gg2 = purrr::map(data, ~ ggplot(., aes(Sepal.Length, Petal.Width)) + geom_point()),
    gg3 = purrr::map(data, ~ ggplot(., aes(Sepal.Length, Petal.Length)) + geom_point()),
    g = purrr::pmap(list(gg1, gg2, gg3), ~ gridExtra::grid.arrange(..1, ..2, ..3))
  )
r2evans
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  • Thank you for quick answers !　 I can solve my problem ! I have overlooked purrr::pmap needs list of lists. Thanks. – Lc_decg Nov 25 '17 at 04:07
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    If it solves your problem, please "accept" it by selecting the checkmark to the left of the answer. – r2evans Nov 25 '17 at 04:08