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rmap-function

R replace the column name by the dataframe name with a map-function

I have a problem replace the column name by the dataframe name with a map-function. I have 25 dataframes with cryptocurrency time series data.

ls(pattern="USD")
[1] "ADA.USD"   "BCH.USD"   "BNB.USD"   "BTC.USD"   "BTG.USD"   "DASH.USD"      "DOGE.USD"  "EOS.USD"   "ETC.USD"   "ETH.USD"   "IOT.USD"
[12] "LINK.USD"  "LTC.USD"   "NEO.USD"   "OMG.USD"   "QTUM.USD"  "TRX.USD"   "USDT.USD"  "WAVES.USD" "XEM.USD"   "XLM.USD"   "XMR.USD"
[23] "XRP.USD"   "ZEC.USD"   "ZRX.USD"

Every object is a dataframe which stands for a cryptocurrency expressed in USD. And every dataframe has 2 clomuns: Date and Close (Closing price). For example: the dataframe "BTC.USD" stands for Bitcoin in USD:

head(BTC.USD)
# A tibble: 6 x 2
Date       Close
1 2015-12-31  430.
2 2016-01-01  434.
3 2016-01-02  434.
4 2016-01-03  431.
5 2016-01-04  433.

Now I want to replace the name of the second column ("Close") by the name of the dataframe ("BTC.USD")

For this case I used the following code:

colnames(BTC.USD)[2] <-deparse(substitute(BTC.USD))

And this code works as I imagined:

head(BTC.USD)
# A tibble: 6 x 2
Date       BTC.USD
1 2015-12-31    430.
2 2016-01-01    434.
3 2016-01-02    434.

Now I am trying to rename all "Close"-columns for all 25 dataframes of cryptocurrency data with a map-function:

names_of_dataframes <- ls.str(mode = "list")
map(names_of_dataframes, colnames(x)[2] <- names_of_dataframes[[i]])

But it doesn't work. Can someone help me?

Solution

  • We get the datasets into list with mget, loop through the list with imap, rename the 2nd column with .y which gives the data.frame object name

    library(tidyverse)
mget(ls(pattern="USD")) %>%         
              imap(~ {nm1 <- .y
                      .x %>% 
                         rename_at(2, ~ nm1) })