<p>您看到的是<code>nunique</code>,而不是<code>count</code>或<code>size</code>:</p>
<pre><code>(pd.merge(df_in.groupby('sender').email_ID.nunique(), # count email sent by ID
df_in.groupby('receiver').email_ID.nunique(), # count email received by ID
left_index=True, # merge on sender
right_index=True, # merge on receiver
how='outer')
.fillna(0) # replace missing with Nan
.rename(columns={'email_ID_x':'number_send', # rename columns as needed
'email_ID_y':'number_received'})
)
</code></pre>
<p>输出:</p>
<pre><code> number_send number_received
Able Boy 2.0 1.0
Johnny C. Cash 0.0 2.0
Mark Angel 0.0 2.0
Mark L. Taylor 2.0 1.0
Toni Z. Zapata 0.0 1.0
debbie bradford 0.0 1.0
michelle fam 0.0 1.0
paul a boyd 0.0 1.0
scott kirk 4.0 0.0
</code></pre>