I am trying to write a line of code to separate a text string whenever a capital letter in encountered without removing the letter. The approach I have taken is as follows:
set.seed(1)
# create a dataframe of fused alpha numeric codes that I wish to separate
df1 <- as.data.frame(matrix(
paste0(sample(LETTERS, 20, replace = TRUE), sample(seq(1, 7, 0.1), 20, replace = TRUE)),
nrow = 10)) %>% unite(col = "ab", sep = "")
df1
# Add a space (" ") before any captial letter encountered
df2 <- df1 %>% mutate(ab = gsub('([[:upper:]])', ' \\1', ab))
df2
# use separate to split the column based on the space
df3 <- df2 %>% separate(col=ab, into=c("a", "b"), sep = " ")
df3
When I run separate I get a warning and the output is not correct:
#Warning message:
#Expected 2 pieces. Additional pieces discarded in 10 rows [1, 2, 3, 4, 5, 6, 7, 8, 9, 10].
#> df3
# a b
#1 Y3
#2 D4.6
#3 G5
#4 A3.4
#5 B5.5
#6 W4.6
#7 K4.6
#8 N4.3
#9 R5.1
#10 S3.4
The contents intended for column "a" have been placed on column "b", whilst those intended for "b" appear to have been removed entirely.
This is because you create a white space before your first letter: to remove it, you can use trimws or str_trim:
df1 %>%
mutate(ab = trimws(gsub('([[:upper:]])', ' \\1', ab))) %>%
separate(col=ab, into=c("a", "b"), sep = " ")
a b
1 Y3 A5.3
2 D4.6 U2.4
3 G5 U4.2
4 A3.4 J2.9
5 B5.5 V4.4
6 W4.6 N1.5
7 K4.6 J1.9
8 N4.3 G5.1
9 R5.1 I4.7
10 S3.4 O5.6