如何删除 R 列中的前几个字符？

Question

My data (csv file) has a column that contains uninformative characters (eg special characters, random lowercase letters), and I want to remove them.

df <- data.frame(Affiliation = c(". Biotechnology Centre, Malaysia Agricultural Research and Development Institute (MARDI), Serdang, Malaysia","**Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, Pulau Pinang, Malaysia","aas Massachusetts General Hospital and Harvard Medical School, Center for Human Genetic Research and Department of Neurology , Boston , MA , USA","ac Albert Einstein College of Medicine , Department of Pathology , Bronx , NY , USA"))

The number of characters I want to remove (eg ".","**","aas","ac") per line is indefinite as shown above.

Expected output:

df <- data.frame(Affiliation = c("Biotechnology Centre, Malaysia Agricultural Research and Development Institute (MARDI), Serdang, Malaysia","Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, Pulau Pinang, Malaysia","Massachusetts General Hospital and Harvard Medical School, Center for Human Genetic Research and Department of Neurology , Boston , MA , USA","Albert Einstein College of Medicine , Department of Pathology , Bronx , NY , USA"))

I was thinking of using dplyr's mutate function, but I'm not sure how to go about it.

Answer 1

If we assume that the valid text starts from the first uppercase onwards, the following works:

library(tidyverse)
df %>% 
  mutate(Affiliation = str_extract(Affiliation, "[:upper:].+"))

Answer 2

Base R regex solution:

df$cleaned_str <- gsub("^\\w+ |^\\*+|^\\. ", "", df$Affiliation)

Tidyverse regex solution:

library(tidyverse)
df %>% 
  mutate(Affiliation = str_replace(Affiliation, "^\\w+ |^\\*+|^\\. ", ""))