R根据另一列拆分一列

Question

I want to split a column based on another. I explain in the following.
here is part of my data:

brand    products
APPLE    IPHONE6SPlus_16G
APPLE    IPHONE6S_64G
APPLE    IPHONE6S_16G
APPLE    IPhone6_32G
APPLE    iPadAir2_64G
APPLE    iPadmini2_16G
APPLE    iPadmini4_64G
HTC      ONEX
Samsung  SamsungGalaxy

I want to split brand based on Products . here is what I actually want.

brand       products
iPhone6S    IPHONE6SPlus_16G
iPhone6S    IPHONE6S_64G
iPhone6S    IPHONE6S_16G
iPhone6     IPhone6_32G
APPLE       iPadAir2_64G
APPLE       iPadmini2_16G
APPLE       iPadmini4_64G
HTC         ONEX
Samsung     SamsungGalaxy

I just want to split APPLE into three new(APPLE, iPhone6S, iPhone6) based on products . If the name in products contains IPHONE6SPlus , IPHONE6S , change brand to iPhone6S. If the name in products contains IPhone6 , change brand to iPhone6. And the remainings do not change.

I think I can use iflese to do, but there are size (ie 16G, 64G, etc.) in products name.
How can I ignore these size and split the data.

Answer 1

We can do this using a couple of methods. Here, is one with sub and ==

v1 <- sub("^(.)(.)(.{5})(.).*", "\\L\\1\\U\\2\\L\\3\\U\\4", df1$products, perl = TRUE)
df1$brand[v1=="iPhone6S"] <- v1[v1 == "iPhone6S"]
df1
#     brand         products
#1 iPhone6S IPHONE6SPlus_16G
#2 iPhone6S     IPHONE6S_64G
#3 iPhone6S     IPHONE6S_16G
#4    APPLE      IPhone6_32G
#5    APPLE     iPadAir2_64G
#6    APPLE    iPadmini2_16G
#7    APPLE    iPadmini4_64G
#8      HTC             ONEX
#9  Samsung    SamsungGalaxy

The sub matches the pattern of first element capture as a group ( (.) ) from the beginning of the string ( ^ ), followed by next element as another group, next 5 elements as third group ( (.{5}) ), followed by another element as a group and the rest of the elements ( .* ). In the replacement, we either change the case to lower ( \\\\L ) or upper ( \\\\U ) for the backreference of those groups ( \\\\1 )

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Or an easier option is with grepl

df1$brand[grepl("IPHONE6S", df1$products)] <- "iPhone6S"

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If the column have both lower and upper case characters, then it can be converted to either one of them using tolower or toupper and then do the processing

df1$brand[grepl("IPHONE6S", toupper(df1$products))] <- "iPhone6S"

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Suppose we want to change multiple elements, this can be done with looping

nm1 <- c("IPAD", "IPHONE", "SAMSUNG")
for(j in nm1) df1$brand[grepl(j, toupper(df1$products))] <- j
df1
#   brand         products
#1  IPHONE IPHONE6SPlus_16G
#2  IPHONE     IPHONE6S_64G
#3  IPHONE     IPHONE6S_16G
#4  IPHONE      IPhone6_32G
#5    IPAD     iPadAir2_64G
#6    IPAD    iPadmini2_16G
#7    IPAD    iPadmini4_64G
#8     HTC             ONEX
#9 SAMSUNG    SamsungGalaxy

Answer 2

'Dirty' solution but I hope it helps :)

x <- c('IPHONE6SPlus','IPHONE6S')
b$new <- grepl(paste(x, collapse = "|"), b$products)
b$brand[b$new==TRUE] <- "Iphone6S"
b$new <- NULL
y <- c('IPhone6')
b$new <- grepl(paste(y, collapse = "|"), b$products)
b$brand[b$new==TRUE] <- "Iphone6"
b$new <- NULL

     brand         products
1 Iphone6S IPHONE6SPlus_16G
2 Iphone6S     IPHONE6S_64G
3 Iphone6S     IPHONE6S_16G
4  Iphone6      IPhone6_32G
5    APPLE     iPadAir2_64G
6    APPLE    iPadmini2_16G
7    APPLE    iPadmini4_64G
8      HTC             ONEX
9  Samsung    SamsungGalaxy