## **<span style="color: steelblue;">II-Path- set working directory</span>**
<span style="color: steelblue;">__Rstudio Working Directory: Location of where you are going to work.__</span>
__Move to the directory which contains your data files, follow:__
__Menu ->Session -> Set working directory -> Choose Directory <span style="color: red;">(which is TP_METABARCODING)</span>__
__Your sequencing data is in the directory data so:__
```{r}
#Put the path directory of your data files in a « variable » named path
path="./data"
```
## <span style="color: steelblue;">III- Read the sequencing files</span>
###<span style="color: steelblue;">__a/list of sequencing files__</span>
The « forward » & « reverse » files are in fastq format with the label:
<span style="color: red;">SAMPLENAME_R1.fastq</span> for the Forward files and <span style="color: red;">SAMPLENAME_R2.fastq</span> for the reverses files.
We use a function implemented in the Fonctions_dada3.R script, which takes the list of R1 files and R2 files and put all quality plot result in one pdf file and save in your current directory TP_METABARCODING.
```{r}
qualityprofile(fnFs,fnRs,'qualityplot.pdf')
```
<span style="color: steelblue;">__open the qualityplot.pdf__</span>
On crée un dossier nommé « Filtered », et à l’intérieur on y met les fichiers nommés « nom du sample” pour R1 et R2. Ces fichiers sont vides pour le moment… c’est une préparation pour l’étape de filtrage.
__<span style="color: steelblue;">FCaution: when using silva_nr_v132_train_set.fa.gz file, you MUST be located in the directory which contains this file (set working directory).</span>__