[Seqinr-forum] read.fasta fails to read a gzipped compressed file from a ftp server

[Haruo Suzuki]

Dear Dr. Lobry: 

Thank you for your speedy response. The problem was solved by using gzcon().

I was wondering if there is any easy way to compute Relative Synonymous Codon Usage (RSCU) for a group of genes.

Based on Examples for `dotchart.uco` at https://cran.r-project.org/web/packages/seqinr/seqinr.pdf
absolute codon frequencies and relative codon frequencies for a collection of all genes can be computed as follows:

    # Load dataset:
    data(ec999)
    # Compute codon usage for all coding sequences:
    ec999.uco <- sapply(ec999, uco, index="eff")
    # Compute absolute codon frequencies
    af <- rowSums(ec999.uco)
    # Compute relative codon frequencies
    rf <- af / sum(af)
    # How to compute Relative Synonymous Codon Usage (RSCU) values for the collection of all genes (average gene)?

Yours sincerely,
Haruo Suzuki

On Apr 22, 2018, at 3:23, Jean Lobry <jean.lobry at univ-lyon1.fr> wrote:

> Found it!
> 
> just use gzcon() to encapsulate the thing, this is explained at:
> 
> http://seqinr.r-forge.r-project.org/src/mainmatter/getseqflat.pdf
> 
> Here is it:
> 
> --------------------- BEGIN
> $ R --quiet
> > library(seqinr)
> > filename <- "ftp://ftp.ncbi.nlm.nih.gov/genomes/all/GCF/000/008/865/GCF_000008865.1_ASM886v1/GCF_000008865.1_ASM886v1_rna_from_genomic.fna.gz"
> > ld <- read.fasta(file = gzcon(url(filename)))
> > head(names(ld))
> [1] "lcl|NC_002695.1_rrna_1" "lcl|NC_002695.1_trna_2" "lcl|NC_002695.1_trna_3"
> [4] "lcl|NC_002695.1_rrna_4" "lcl|NC_002695.1_rrna_5" "lcl|NC_002695.1_trna_6"
> 
> ----------------------- END
> 
> Best,
> 
> JLO
> 
> Le 21/04/2018 à 20:02, Jean Lobry a écrit :
>> Dear all,
>> I was able to reproduce the well documented faulty behaviour as follows:
>> -------------------------- BEGIN ------------------------------------
>> $ R --quiet
>> > library("seqinr")
>> > filename <- "ftp://ftp.ncbi.nlm.nih.gov/genomes/all/GCF/000/008/865/GCF_000008865.1_ASM886v1/GCF_000008865.1_ASM886v1_rna_from_genomic.fna.gz"  > ld <- read.fasta(file = filename)
>> Error in substr(lines, 1L, 1L) :
>>   chaîne de charactères multioctets incorrecte à '<aa><89><b4>b<68><8d><a4>c0<ed><B$<97>    O<eb>3:<d2>ڀR 46<a4>L<9b><91>d<ba><b2>9<a6><c4>k!<d2>z<a6>G<8d>4<bb> פa0>2H[<ac>X<d2>VP<b0>a<d2>tj<84><e6><99>&<95><8e><86>Kt<ac>OHZ:@<d7>.
>> |Sэ<e8><81>#<e9><ae><9a><9f>ab><bb>b<ac>ab>W<d7>W<8c><95><93><8d><d5><d0>/<8c><d5>]6<?<fb><cd><f5>ա<8d>\e5><86>a<b2>Qw<b0>Q<b4><90>` <8e>#-M<a8><9d<f5><db><9a>
>>                                                  z
>> d$|<8a>4r<dc>¥<d7><f3><eb><e7><ae>a<d7>p<8c>+\??<c2>5<e8><8e>p<f9><d6><e1>!<aa><94>"`E2<a1>iR<ab><88><e6><89>' De plus : There were 27 warnings (use warnings() to see them)
>> > sessionInfo()
>> R version 3.4.1 (2017-06-30)
>> Platform: x86_64-apple-darwin15.6.0 (64-bit)
>> Running under: macOS Sierra 10.12.6
>> Matrix products: default
>> BLAS: /Library/Frameworks/R.framework/Versions/3.4/Resources/lib/libRblas.0.dylib
>> LAPACK: /Library/Frameworks/R.framework/Versions/3.4/Resources/lib/libRlapack.dylib
>> locale:
>> [1] fr_FR.UTF-8/fr_FR.UTF-8/fr_FR.UTF-8/C/fr_FR.UTF-8/fr_FR.UTF-8
>> attached base packages:
>> [1] stats     graphics  grDevices utils     datasets  methods   base
>> other attached packages:
>> [1] seqinr_3.4-5
>> loaded via a namespace (and not attached):
>> [1] compiler_3.4.1 ade4_1.7-8
>> > q()
>> Save workspace image? [y/n/c]: n
>> -------------------------- END ------------------------------------
>> Rings a bell to me, I'll post a solution asap.
>> Best,
>> JLO
>> -------- Message transféré --------
>> Sujet :     Re: Error in library(help=seqinr)
>> Date :     Sun, 22 Apr 2018 02:21:23 +0900
>> De :     Haruo Suzuki <haruo at sfc.keio.ac.jp>
>> Pour :     Simon Penel <simon.penel at univ-lyon1.fr>
>> Copie à :     jean.lobry at univ-lyon1.fr
>> Dear Simon,
>> The `read.fasta` function of seqinr package failed to load the gzipped FASTA file directly from the ftp site, simply by specifying a full URL, as shown in attachment.
>> Yours sincerely,
>> Haruo Suzuki
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