<p>You will need to &quot;read&quot; your data. There are packages that can read Excel files directly but I would save the data as csv first and then use <code>read.csv()</code>. The following would create a new column with your desired output:</p>
<pre><code>data_frame<span class="math-container">$new_col &lt;- substring(data_frame$</span>col_with_seqs, 1, 20)
</code></pre>
<p>Alternatively you can just use Excel's <code>LEFT()</code> since your data is already in Excel:</p>
<pre><code>=LEFT(A1, 20)
</code></pre>

CC BY-SA 4.0
2022-11-28T18:54:17.443Z
2022-11-28T18:54:17.443Z
haci
<p>I have an Excel sheet from the CRISPR library where I have sequences of gRNAs (with 30 nucleotides) in a column and I only need to keep the first 20 nucleotides for those gRNAs and delete the rest nucleotides. The column has 1000 rows that have 30 nucleotide gRNA sequences. How can I delete extra nucleotides using R</p>

CC BY-SA 4.0
2022-11-27T11:44:29.657Z
Please clarify your specific problem or provide additional details to highlight exactly what you need. As it's currently written, it's hard to tell exactly what you're asking.
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<r><scrnaseq><bioconductor><crispr>
Keep first 20 nucleotides of sequences using R
# Keep first 20 nucleotides of sequences using R

(Asked by: username_0 on 2022-11-27)

I have an Excel sheet from the CRISPR library where I have sequences of gRNAs (with 30 nucleotides) in a column and I only need to keep the first 20 nucleotides for those gRNAs and delete the rest nucleotides. The column has 1000 rows that have 30 nucleotide gRNA sequences. How can I delete extra nucleotides using R

**Tags:** r, scrnaseq, bioconductor, crispr
> **Comments:**
> **username_1**: Please clarify your specific problem or provide additional details to highlight exactly what you need. As it's currently written, it's hard to tell exactly what you're asking.  

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## 1 answers

### Answer by username_2 on 2022-11-28. Score: 2

You will need to "read" your data. There are packages that can read Excel files directly but I would save the data as csv first and then use read.csv(). The following would create a new column with your desired output:
data_frame$new_col <- substring(data_frame$col_with_seqs, 1, 20)

Alternatively you can just use Excel's LEFT() since your data is already in Excel:
=LEFT(A1, 20)


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