Use table() inside dataframes stored in a list to create new dataframes

Question

I have the dataframe below:

library lubridate

eventtime<-c("2020-02-07 22:06:00","2020-02-07 22:00:00","2020-02-07 21:46:00")
eventvalue<-c("home","work",'exit')
geof<-data.frame(eventtime,eventvalue)

Then I use a list to store them and assign the list elements to different data.frames using:

library(lubridate)
library(tidyverse)

list1 <- geof %>%
  split(.$eventvalue) %>%
  bind_rows() %>%
  mutate(EventHour = hour(eventtime)) %>%
  split(.$eventvalue)

for (i in names(list1)) setNames(assign(i, data.frame(list1[[i]])), names(list1))

I would like then to use table() based on EventHour for each dataframe to create new dataframes with the frequency of each EventHour and then rename those columns

#table the events by count of hours
tablegeh<-data.frame(table(home$EventHour))

colnames(tablegeh)<-c("Hour","Frequency")

Allan Cameron · Accepted Answer · 2020-03-06 12:56:23Z

2

You can use lapply:

lapply(list1, function(x) table(x$EventHour))
#> $exit
#> 21 
#>  1 
#>
#> $home
#> 22 
#>  1 
#>
#> $work
#> 22 
#>  1

Obviously, you only have a single entry in each data frame, so the "tables" don't look much like tables!

answered Mar 6, 2020 at 12:56

Allan Cameron

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4 Comments

firmo23 Over a year ago

how can I save those new dataframes and rename their columns as well?yes they re just examples

Allan Cameron Over a year ago

@firmo23 you can choose whichever names you want if you do, for example, lapply(list1, function(x) setNames(as.data.frame(table(x$EventHour)), c("Hour", "n"))). If you want to save them, you can save the whole list as an RDS, or convert them all into one big data frame using do.call(rbind, list1), or save each one to csv using mapply(function(x) write.csv(x, y), list1, c("exit.csv", "home.csv", "work.csv"))

firmo23 Over a year ago

thank you but I do not mean to save them in a file but as separated dataframes for later use

Allan Cameron Over a year ago

@firmo23 if you do list2 <- lapply(list1, function(x) table(x$EventHour)) then you can access each one by e.g. list2$home, which gives you the whole home data frame. If you like you can store a copy outside the list with home <- list2$home

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