R - Adding Data Frame to Matrix

Question

I am trying to transform a data frame (treating as a vector) with locational data and a value onto a matrix that uses locational data as it's row and column names.

(Run snippets to see layout examples.)

Example of the vector:

 <table>
  <tr>
    <th>"Longitude"</th>
    <th>"Latitude"</th>
    <th>"Value"</th>
  </tr>
  <tr>
    <td>1</td>
    <td>2</td>
    <td>10</td>
  </tr>
  <tr>
    <td>3</td>
    <td>3</td>
    <td>100</td>
  </tr>
  <tr>
    <td>2</td>
    <td>1</td>
    <td>65</td>
  </tr>
</table>

Example of the matrix:

 <table>
  <tr>
    <th></th>
    <th>1</th>
    <th>2</th>
    <th>3</th>
  </tr>
  <tr>
    <th>1</th>
    <td>0.00</td>
    <td>0.00</td>
    <td>0.00</td>
  </tr>
  <tr>
    <th>2</th>
    <td>0.00</td>
    <td>0.00</td>
    <td>0.00</td>
  </tr>
  <tr>
    <th>3</th>
    <td>0.00</td>
    <td>0.00</td>
    <td>0.00</td>
  </tr>
</table>

The result I want is:

 <table>
  <tr>
    <th></th>
    <th>1</th>
    <th>2</th>
    <th>3</th>
  </tr>
  <tr>
    <th>1</th>
    <td>0.00</td>
    <td>65.00</td>
    <td>0.00</td>
  </tr>
  <tr>
    <th>2</th>
    <td>10.00</td>
    <td>0.00</td>
    <td>0.00</td>
  </tr>
  <tr>
    <th>3</th>
    <td>0.00</td>
    <td>0.00</td>
    <td>100.00</td>
  </tr>
</table>

Essentially, I want to treat the data frame as a series of vectors and transform them onto the matrix but my past attempts have resulted in the matrix transforming itself into a list instead.

Does anyone know how to do this?

Thank you in advance.

Arghh. This is not the purpose of code snippets. Just copy your input as text and use the code markup. — Roland, Mar 20 '19 at 14:13
Even better would be to use `dput` to paste your data in a format we could work with. — divibisan, Mar 20 '19 at 14:19

score 0 · Answer 1 · answered Mar 20 '19 at 14:07

0

We can do this easily with xtabs from base R

out <- xtabs(Value ~ Latitude + Longitude, df1)
names(dimnames(out)) <- NULL
out
#    1   2   3
#1   0  65   0
#2  10   0   0
#3   0   0 100

answered Mar 20 '19 at 14:07

akrun

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R - Adding Data Frame to Matrix

1 Answers1