pandas update dataframe row with new value
<p>I have a text file which has been read into pandas by <code>df1 = pandas.read_csv(r'fruits.txt', sep=',')</code></p>

<pre><code>    item  freshness
0   apple    2.2
1   pear     0.0
</code></pre>

<p>and a series of calculations that would yield the result of <code>apple = 2.3</code></p>

<p>Is it possible to do a <code>pandas.update</code> so that I can update the value of <code>freshness</code> for <code>apple</code> in the dataframe to <code>2.3</code>?</p>