r 合并命令返回列表，而不是数据框

Question

Yesterday merge kept returning a list instead of a data frame, separating out each column as a separate element in the list. When I tried the join command from plyr, it was making all but one of my non-join by columns take on the exact same value in every row. Today the merge command worked, but I'm worried in case this ever happens again. I don't know how to fix it. Has anyone ever heard of this problem? EDIT: It is no longer working again.

I am trying to merge 2 data frames using the merge command. The data frames are tab2 and tab 4 and they both have 4 columns in common by which I am trying to merge. Tab2 has one extra columns, col5, while tab4 has several extra columns named sum1, ... sum7.

This command:

temp <- merge(tab2, tab4, by = c("year", "month", "n_make", "n_mod"), all = TRUE, sort = FALSE)

produced an error: Error in merge(tab2, tab4, by = c("year", "month", "n_make", "n_mod"), : unused arguments (by = c("year", "month", "n_make", "n_mod"), all = TRUE, sort = FALSE)

When I eliminated the "by" part, the error was the same, just mentioning the "all" and "sort" parts. When I eliminated the all and sort parts:

tmp <- merge(tab2, tab4)

the command went through, but instead of giving me a data frame, it gave me a list, where the first element was the col_5 column from tab2 and it had as many elements as tab2 has rows. The other entries were named after all my other columns, including the merge by columns, and they only had as many entries as tab4.

I would really appreciate ANY information people can give me on this problem. I cannot risk it happening again. The code I am writing has to be combined with other code at work and will be run on at least a monthly basis, so I need it to work all the time.

Here is the join command which did not work either:

library(plyr)
tmp <- join(tab2, tab4, type = "full")

EDIT: reproducible example Since the data is proprietary, I rewrote a small example and it still doesn't work. I'm including packages I included in case one of them is messing things up:

library(RODBC)
library(RPostgres)              
library(DBI)
library(RPostgreSQL)
library(installr)
library(devtools)
library(remotes)
library(dbplyr)
library(dplyr)
# library(dbplot)   # not avaiable for R version 3.6.2
library(ggplot2)
library(modeldb)
library(tidypredict)
library(config)
library(inspectdf)
library(vcdExtra)
library(vcd)
library(janitor)
library(plyr)
library(openintro)
library(lattice)

year = c(2015, 2015, 2015, 2016, 2016, 2016, 2017, 2017, 2017, 2018, 2018, 2018, 2019, 2019, 2019)
month = c(1, 1, 3, 1, 2, 2, 1, 2, 3, 1, 2, 3, 2, 2, 3)
n_make = c("A", "B", "A", "A", "A", "B", "A", "B", "C", "A", "B", "C", "B", "C", "C")
n_mod = c(7, 8, 7, 7, 9, 8, 7, 8, 6, 7, 8, 6, 8, 6, 5)
col5 = c(24, 38, 92, 41, 63, 19, 14, 8, 56, 73, 80, 13, 21, 42, 66)
t2 <-data.frame(year, month, n_make, n_mod, col5)
head(t2, 15)


year = c(2015, 2015, 2015, 2015, 2016, 2016, 2017, 2017, 2018, 2018, 2019, 2019, 2019, 2000)
month = c(1, 1, 1, 3, 1, 2, 2, 3, 1, 2, 1, 2, 2, 1)
n_make = c("A", "B", "C", "A", "A", "A", "B", "C", "A", "B", "B", "B", "C", "C")
n_mod = c(7, 8, 6, 7, 7, 9, 8, 6, 7, 8,  8, 8, 6, 5)
x = c(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
y = c(14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1)
t4 <- data.frame(year, month, n_make, n_mod, x, y)
head(t4, 14)

# This is producing error messages.
t <- merge(t2, t4, by = c("year", "month", "n_make", "n_mod"), all = TRUE, sort = FALSE) 
t

#This is producing a regular list instead of a dataframe.
t <- merge(t2, t4)
t

Answer 1

I believe the config package is masking the base merge command. By erasing all output and restarting R with that package commented out, the merge command now works.

It's funny, because I tried base::merge just in case a masking was the problem, but that didn't work.