On Sat, 18 Oct 2014, Anna Zakrisson Braeunlich wrote:

Thank you! That was a easy and fast solution!

If it was so easy, why couldn't you adapt Ista's solution? I suspect it is because you don't understand his suggestion.

May I post a follow-up question? (I am not sure if this would rather should be posted as a new question, but I post it here and then I can re-post it if this is the wrong place to ask this). I am ever so grateful for your help!

This probably should have been a new thread, but I will bite anyway.

/Anna


######################### FOLLOW-UP QUESTION 
####################################

df1 <- data.frame(cbind(Identifier = c("M123.B23.VJHJ", "M123.B24.VJHJ",
                                      "M123.B23.VLKE", "M123.B23.HKJH",
                                      "M123.B24.LKJH"),
                                      Sequence = c("ATATATATATA", "ATATATATATA",
                                                   "ATATAGCATATA", 
"ATATATAGGGTA",
                                                   "ATCGCGCGAATA")))

Just because R has a habit of making factors at the drop of a hat doesn't mean that if your data are still not ready to be treated as factors that you have to accept what it does. When you read the data in via read.csv you can use the colClasses argument or the stringsAsFactors argument to stop that. You can use stringsAsFactors when you create the data frame also, and you can always go back and turn any particular column into a factor after you are done manipulating characters.

Also, somewhere you picked up the bad habit of using cbind before you make your data frame... that is almost never a good idea, because in data frames each column can be have its own storage mode, while cbind creates a matrix where every element must have the same storage mode.

df1 <- data.frame( Identifier = c( "M123.B23.VJHJ", "M123.B24.VJHJ"
                                 , "M123.B23.VLKE", "M123.B23.HKJH"
                                 , "M123.B24.LKJH" )
                 , Sequence = c( "ATATATATATA", "ATATATATATA"
                               , "ATATAGCATATA", "ATATATAGGGTA"
                               , "ATCGCGCGAATA" )
                 , stringsAsFactors=FALSE
                 )



# as a follow-up question:
# How can I split the identifier in df1 above into several columns based on the
# separating dots? The real data includes thousands of rows.
# This is what I want it to look like in the end:

df1_solution <- data.frame(cbind(Identifier1 = c("M123", "M123",
                                      "M123", "M123",
                                      "M123"),
                       Identifier2 = c("B23", "B24", "B23", "B23", "B24"),
                       Identifier3 = c("VJHJ", "VJHJ", "VLKE", "HKJH", "LKJH"),
                       Sequence = c("ATATATATATA", "ATATATATATA",
                                    "ATATAGCATATA", "ATATATAGGGTA",
                                    "ATCGCGCGAATA")))

df1_solution <- data.frame( Identifier1 = c( "M123", "M123"
                                           , "M123", "M123"
                                           , "M123" )
                          , Identifier2 = c( "B23", "B24", "B23"
                                           , "B23", "B24" )
                          , Identifier3 = c( "VJHJ", "VJHJ"
                                           , "VLKE", "HKJH", "LKJH")
                          , Sequence = c( "ATATATATATA", "ATATATATATA"
                                        , "ATATAGCATATA", "ATATATAGGGTA"
                                        , "ATCGCGCGAATA" )
                          , stringsAsFactors=FALSE
                         )


# I am very grateful for your help! I am no whiz at R and everything I know
# is self-taught. Therefore, some basics can turn out to be quite some
# obsatcles for me.
# /Anna

Pretty much all of us are here to teach ourselves R, Anna. Keep reading other people's questions. Learn to try each fragment alone at the command line to figure out what is happening. Use the str() function frequently.

# the basic split
parts <- strsplit( as.character( df1$Identifier ), ".", fixed=TRUE )

# extension of Ista's approach to assembly
ans1 <- data.frame( Identifier1 = rep( NA, nrow( ans1 ) )
                  , Identifier2 = rep( NA, nrow( ans1 ) )
                  , Identifier3 = rep( NA, nrow( ans1 ) )
                  , stringsAsFactors = FALSE
)
# note all memory is pre-allocated above... avoid successively
# accumulating rows with rbind... that would be very slow
for ( rw in seq_along( df1$Identifier ) ) {
  v <- parts[[ rw ]]
  ans1[ rw, "Identifier1" ] <- v[ 1 ]
  ans1[ rw, "Identifier2" ] <- v[ 2 ]
  ans1[ rw, "Identifier3" ] <- v[ 3 ]
}
ans1$Sequence <- df1$Sequence

#---- alternative method of assembly
# uses "list-to-data.frame apply" from plyr package
library(plyr)
ans2 <- ldply( parts
             , function( v ) { # called once for each item in parts list
                      # all single-row data frames created in this
                      # function are concatenated at once by ldply to
                      # make one big data.frame "ans2"
                      data.frame( Identifier1=v[1]
                                , Identifier2=v[2]
                                , Identifier3=v[3]
                                , stringsAsFactors=FALSE
                                )
               }
             )
ans2$Sequence <- DF$Sequence


<((((?>`?. . ? `?. .? `?. . ><((((?>`?. . ? `?. .? `?. .><((((?>`?. . ? `?. .? `?. 
.><((((?>

Anna Zakrisson Braeunlich
PhD student

Department of Ecology, Environment and Plant Sciences
Stockholm University
Svante Arrheniusv. 21A
SE-106 91 Stockholm
Sweden/Sverige

Lives in Berlin.
For paper mail:
Katzbachstr. 21
D-10965, Berlin
Germany/Deutschland

E-mail: anna.zakris...@su.se
Tel work: +49-(0)3091541281
Mobile: +49-(0)15777374888
LinkedIn: http://se.linkedin.com/pub/anna-zakrisson-braeunlich/33/5a2/51b

<((((?>`?. . ? `?. .? `?. . ><((((?>`?. . ? `?. .? `?. .><((((?>`?. . ? `?. .? `?. 
.><((((?>

________________________________________
From: Ista Zahn [istaz...@gmail.com]
Sent: 13 October 2014 15:42
To: Anna Zakrisson Braeunlich
Cc: r-help@r-project.org
Subject: Re: [R] seqinr ?: Splitting a factor name into several columns. 
Dealing with metabarcoding data.

Hi Anna,


On Sun, Oct 12, 2014 at 3:24 AM, Anna Zakrisson Braeunlich
<anna.zakris...@su.se> wrote:
Hi,

I have a question how to split a factor name into different columns. I have 
metabarcoding data and need to merge the FASTA-file with the taxonomy- and 
counttable files (dataframes). To be able to do this merge, I need to isolate 
the common identifier, that unfortunately is baked in with a lot of other 
labels in the factor name eg:
sequence identifier: 
M01271_77_000000000.A8J0P_1_1101_10150_1525.1.322519.sample_1.sample_2

I want to split this name at every "." to get several columns:
column1: M01271_77_000000000
column2: A8J0P_1_1101_10150_1525
column3: 1
column4: 322519
column5: sample_1
column6: sample_2

I must add that I have no influence on how these names are given. This is how 
thay are supplied from Illumina Miseq. I just need to be able to deal with it.

Here is some extremely simplified dummy data to further show the issue at hand:

df1 <- data.frame(cbind(X = 1:10, Y = rnorm(10)),
                  Z.identifierA.B1298712 = factor(rep(LETTERS[1:2], each = 5)))
df2 <- data.frame(cbind(B = 13:22, K = rnorm(10)),
                  Q.identifierA.B4668726 = factor(rep(LETTERS[1:2], each = 5)))

# I have metabarcoding data with one FASTA-file, one count table and one 
taxonomy file
# Above dummy data is just showing the issue at hand. I want to be able to 
merge my three
# original data frames (here, the dummy data is only two dataframes). The 
problem is that
# the only identifier that is commmon for the dataframes is "hidden" in the
# factor name eg: Z.identifierA.1298712 and Q.identifierA.4668726. I hence need 
to be able
# to split this name up into different columns to get "identifierA" alone as 
one column name
# Then I can merge the dataframes.
# How can I do this in R. I know that it can be done in excel, but I would like 
to
# produce a complete R-script to get a fast pipeline and avoid copy and paste 
errors.
# This is what I want it to look:

df1.goal <- data.frame(cbind(X = 1:10, Y = rnorm(10)),
                  Z = factor(rep(LETTERS[1:2], each = 5)),
                  identifierA = factor(rep(LETTERS[1:2], each = 5)),
                  B1298712 = factor(rep(LETTERS[1:2], each = 5)))

Use strsplit to separate the components, something like

separateNames <- strsplit(names(df1)[3], split = "\\.")[[1]]
for(name in separateNames) {
   df1[[name]] <- df1[[3]]
}
df1[[3]] <- NULL

Best,
Ista


# Many thank's and with kind regards
Anna Zakrisson

<((((?>`?. . ? `?. .? `?. . ><((((?>`?. . ? `?. .? `?. .><((((?>`?. . ? `?. .? `?. 
.><((((?>

Anna Zakrisson Braeunlich
PhD student

Department of Ecology, Environment and Plant Sciences
Stockholm University
Svante Arrheniusv. 21A
SE-106 91 Stockholm
Sweden/Sverige

Lives in Berlin.
For paper mail:
Katzbachstr. 21
D-10965, Berlin
Germany/Deutschland

E-mail: anna.zakris...@su.se
Tel work: +49-(0)3091541281
Mobile: +49-(0)15777374888
LinkedIn: http://se.linkedin.com/pub/anna-zakrisson-braeunlich/33/5a2/51b

<((((?>`?. . ? `?. .? `?. . ><((((?>`?. . ? `?. .? `?. .><((((?>`?. . ? `?. .? `?. 
.><((((?>

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