擅长:python、mysql、java
<p>你可以这样做:</p>
<pre><code>import pandas as pd
df = pd.DataFrame()
tree_species = ["Acer rubrum", "Quercus bicolor", "Quercus bicolor", "aabbccdd"]
no_of_trunks = [1,1,1,0]
df["Tree Species"] = tree_species
df["Number of Trunks"] = no_of_trunks
df.groupby('Tree Species').sum() #This will create a pandas dataframe
df.groupby('Tree Species')['Number of Trunks'].sum() #This will create a pandas series.
</code></pre>
<p>你也可以通过使用字典来做同样的事情:</p>
<pre><code>tree_species = ["Acer rubrum", "Quercus bicolor", "Quercus bicolor", "aabbccdd"]
no_of_trunks = [1,1,1,0]
d = {}
for key, trunk in zip(tree_species, no_of_trunks):
if not key in d.keys():
d[key] = 0
d[key] += trunk
print(d)
</code></pre>