R: add a new column to dataframes from a function

Question

I have many tibbles similar to this:

dftest_tw <- structure(list(text = c("RT @BitMEXdotcom: A new high: US$500M turnover in the last 24 hours, over 80% of it on $XBTUSD. Congrats to the team and thank you to our u…", 
"RT @Crowd_indicator: Thank you for this nice video, @Nicholas_Merten", 
"RT @Crowd_indicator: Review of #Cindicator by DataDash: t.co/D0da3u5y3V"
), Tweet.id = c("896858423521837057", "896858275689398272", "896858135314538497"
), created.date = structure(c(17391, 17391, 17391), class = "Date"), 
    created.week = c(33, 33, 33)), .Names = c("text", "Tweet.id", 
"created.date", "created.week"), row.names = c(NA, -3L), class = c("tbl_df", 
"tbl", "data.frame"))

For testing, we add another one:

dftest2_tw <- dftest_tw

I have this list of my df:

myUserList <- ls(,pattern = "_tw")

What I am looking to do is:

1- add a new column named Twitter.name

2- fill the column with the df name, all this in a function. The following code works for each df taken one by one:

dftest_tw %>% rowwise() %>% mutate(Twitter.name = myUserList[1])

The desired result is this:

MyRes <- structure(list(text = c("RT @BitMEXdotcom: A new high: US$500M turnover in the last 24 hours, over 80% of it on $XBTUSD. Congrats to the team and thank you to our u…", 
"RT @Crowd_indicator: Thank you for this nice video, @Nicholas_Merten", 
"RT @Crowd_indicator: Review of #Cindicator by DataDash: t.co/D0da3u5y3V"
), Tweet.id = c("896858423521837057", "896858275689398272", "896858135314538497"
), created.date = structure(c(17391, 17391, 17391), class = "Date"), 
    created.week = c(33, 33, 33), retweet = c(0, 0, 0), custom = c(0, 
    0, 0), Twitter.name = c("dftest_tw", "dftest_tw", "dftest_tw"
    )), .Names = c("text", "Tweet.id", "created.date", "created.week", 
"retweet", "custom", "Twitter.name"), class = c("rowwise_df", 
"tbl_df", "tbl", "data.frame"), row.names = c(NA, -3L))

When it comes to write a function to be thereafter been applied to all my df (more than 100), I can't achieve it. Any help would be appreciated.

I have been following this https://stackoverflow.com/questions/31754693/r-add-a-new-variable-to-dataframes-whose-value-is-equal-to-the-name-of-the-data , but I can't get a result — gabx, Aug 31 '17 at 15:30

akrun · Accepted Answer · 2017-08-31T16:38:53.883

1

We can use tidyverse options. Get the value of multiple string objects with mget, then with map2 from purrr, create the new column 'Twitter.name in each dataset of the list with corresponding string element of 'myUserList`

library(tidyverse) 
lst <- mget(myUserList) %>% 
          map2(myUserList,  ~mutate(.data = .x, Twitter.name = .y))

If we need to modify the objects in the global environment, use list2env

list2env(lst, envir = .GlobalEnv)

edited Aug 31 '17 at 16:38

answered Aug 31 '17 at 15:35

akrun

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this code will print the result on my screen, but the original df didn't change in my workspace. – gabx Aug 31 '17 at 16:36
@gabx It is easy to do that. But I would keep this in a `list` instead of creating objects in the global environment. Modified the answer – akrun Aug 31 '17 at 16:38
1

exactly the solution I was looking for. Thank you so much – gabx Aug 31 '17 at 17:26
I am looking to save our results with another name, say adding ".final" at the end. This is to have a new list. This doesn't work: assign(paste(myUserList, ".final", sep = ""), myUserList). Any solution? – gabx Aug 31 '17 at 19:49
@gabx If that is the case, change the names of the `lst` with `names(lst) <- paste0(names(lst), ".final")` and then use the `list2env` – akrun Sep 01 '17 at 03:33
@gabx Please check if you have the same structure as in the sample i.e. `str(yourrealdata)` – akrun Sep 01 '17 at 08:56

R: add a new column to dataframes from a function

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