如果我将分组数据帧传递给函数,然后更改分组变量的名称,原始数据框的分组将更改为新名称.当函数返回时(我没有返回更改的数据帧),原始数据框的名称保持不变,但分组更改为不存在的名称.
# test scoping of group_by() which appears to change groups
library(dplyr)
muck_up_group<-function(mydf){
mydf<-mydf %>% rename(UhOh=Species)
}
dont_muck_up_group<-function(mydf){
mydf<-mydf %>% ungroup()
mydf<-mydf %>% rename(UhOh=Species)
}
data("iris")
iris<-as_tibble(iris) %>% group_by(Species)
iris
# A tibble: 150 x 5
# Groups: Species [3]
# Sepal.Length Sepal.Width Petal.Length Petal.Width Species
# <dbl> <dbl> <dbl> <dbl> <fctr>
# 1 5.1 3.5 1.4 0.2 setosa
muck_up_group(iris) # original grouping changed to column name that doesn't exist
iris
# A tibble: 150 x 5
# Groups: UhOh [3]
# Sepal.Length Sepal.Width Petal.Length Petal.Width Species
# <dbl> <dbl> <dbl> <dbl> <fctr>
# 1 5.1 3.5 1.4 0.2 setosa
#restore original state
iris<-as_tibble(iris) %>% group_by(Species)
dont_muck_up_group(iris) # original grouping preserved
iris
# A tibble: 150 x 5
# Groups: Species [3]
# Sepal.Length Sepal.Width Petal.Length Petal.Width Species
# <dbl> <dbl> <dbl> <dbl> <fctr>
# 1 5.1 3.5 1.4 0.2 setosa
我可以理解为什么改变分组变量的名称可能是不好的做法,但这是允许的.这似乎是当通过值传递内容时通过引用传递的变量的属性的示例(正如我们理解R通常所做的那样).
> sessionInfo()
R version 3.4.0 (2017-04-21)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows 7 x64 (build 7601) Service Pack 1
Matrix products: default
locale:
[1] LC_COLLATE=English_United States.1252 LC_CTYPE=English_United States.1252
[3] LC_MONETARY=English_United States.1252 LC_NUMERIC=C
[5] LC_TIME=English_United States.1252
attached base packages:
[1] graphics grDevices utils datasets stats methods base
other attached packages:
[1] lubridate_1.6.0 bindrcpp_0.2 mFilter_0.1-3
[4] ggrepel_0.6.5 reshape2_1.4.2 scales_0.4.1
[7] purrr_0.2.3 readr_1.1.1 tidyr_0.7.0
[10] tibble_1.3.4 tidyverse_1.1.1 knitr_1.17
[13] Rblpapi_0.3.6 stringr_1.2.0 rvest_0.3.2
[16] xml2_1.1.1 devtools_1.13.3 dplyr_0.7.2
[19] plyr_1.8.4 ggplot2_2.2.1 PerformanceAnalytics_1.4.3541
[22] xts_0.10-0 zoo_1.8-0
loaded via a namespace (and not attached):
[1] Rcpp_0.12.12 lattice_0.20-35 assertthat_0.2.0 rprojroot_1.2 digest_0.6.12
[6] psych_1.7.5 R6_2.2.2 cellranger_1.1.0 backports_1.1.0 evaluate_0.10.1
[11] httr_1.3.1 highr_0.6 rlang_0.1.2 curl_2.8.1 lazyeval_0.2.0
[16] readxl_1.0.0 TTR_0.23-2 tidyquant_0.5.3 rmarkdown_1.6 labeling_0.3
[21] foreign_0.8-67 munsell_0.4.3 broom_0.4.2 compiler_3.4.0 modelr_0.1.1
[26] pkgconfig_2.0.1 base64enc_0.1-3 mnormt_1.5-5 htmltools_0.3.6 tidyselect_0.1.1
[31] withr_2.0.0 Quandl_2.8.0 grid_3.4.0 nlme_3.1-131 jsonlite_1.5
[36] gtable_0.2.0 magrittr_1.5 quantmod_0.4-10 stringi_1.1.5 RColorBrewer_1.1-2
[41] tools_3.4.0 forcats_0.2.0 glue_1.1.1 hms_0.3 rsconnect_0.8.5
[46] parallel_3.4.0 yaml_2.1.14 colorspace_1.3-2 memoise_1.1.0 bindr_0.1
[51] haven_1.1.0
>
错误？谢谢.