<p dir="auto">When I perform the following:</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="# Import relevant libraries
import pandas as pd
import seaborn as sns
import matplotlib.pyplot as plt
%matplotlib inline

# set up the dataframe
ids = range(12)
surv = [0,0,1,1] * 3
fare = list(range(3, 3*13, 3))
sex = ['m', 'f', 'f', 'm'] * 3
emb = ['A'] * 4 +['B']*4 + ['C'] * 4
titles = ['id', 'Survived', 'Fare', 'Sex', 'Embarked']

data = pd.DataFrame(columns=titles)

data['id'] = ids
data['Survived'] = surv
data['Fare'] = fare
data['Sex'] =sex
data['Embarked'] = emb

# inspect the data - esp. values for fare and sex
data"><pre class="notranslate"><code class="notranslate"># Import relevant libraries
import pandas as pd
import seaborn as sns
import matplotlib.pyplot as plt
%matplotlib inline

# set up the dataframe
ids = range(12)
surv = [0,0,1,1] * 3
fare = list(range(3, 3*13, 3))
sex = ['m', 'f', 'f', 'm'] * 3
emb = ['A'] * 4 +['B']*4 + ['C'] * 4
titles = ['id', 'Survived', 'Fare', 'Sex', 'Embarked']

data = pd.DataFrame(columns=titles)

data['id'] = ids
data['Survived'] = surv
data['Fare'] = fare
data['Sex'] =sex
data['Embarked'] = emb

# inspect the data - esp. values for fare and sex
data
</code></pre></div>
<p dir="auto"><a target="_blank" rel="noopener noreferrer nofollow" href="https://cloud.githubusercontent.com/assets/1828588/25071180/f0c68ae8-22b0-11e7-9290-bb235b445b80.png"><img width="268" alt="data" src="https://cloud.githubusercontent.com/assets/1828588/25071180/f0c68ae8-22b0-11e7-9290-bb235b445b80.png" style="max-width: 100%;"></a></p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="# plot the data - here the bug manifests
grid = sns.FacetGrid(data, row='Embarked', col='Survived', size=2.2, aspect=1.6)
grid.map(sns.barplot, 'Sex', 'Fare', alpha=.5, ci=None)
grid.add_legend()"><pre class="notranslate"><code class="notranslate"># plot the data - here the bug manifests
grid = sns.FacetGrid(data, row='Embarked', col='Survived', size=2.2, aspect=1.6)
grid.map(sns.barplot, 'Sex', 'Fare', alpha=.5, ci=None)
grid.add_legend()
</code></pre></div>
<p dir="auto"><a target="_blank" rel="noopener noreferrer nofollow" href="https://cloud.githubusercontent.com/assets/1828588/25071175/c4466574-22b0-11e7-81b5-7aa732e05785.png"><img width="520" alt="facetgrid" src="https://cloud.githubusercontent.com/assets/1828588/25071175/c4466574-22b0-11e7-81b5-7aa732e05785.png" style="max-width: 100%;"></a></p>
As you can see, the order of the 'm' and 'f' bars in the graphs in the first columns have been switched, even though the labels on the axes suggest otherwise.
<p dir="auto">Versions:<br>
pandas    :  0.19.2<br>
seaborn   :  0.7.1<br>
matplotlib:  2.0.0</p>
<p dir="auto">The <code class="notranslate">area</code> method for calculating the width of boxenplot letter-value boxes is:</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="'area': lambda h, i, k: (1 - 2**(-k + i - 2)) / h}"><pre class="notranslate"><code class="notranslate">'area': lambda h, i, k: (1 - 2**(-k + i - 2)) / h}
</code></pre></div>
<p dir="auto">in <a href="https://github.com/mwaskom/seaborn/blob/master/seaborn/categorical.py#L1890">https://github.com/mwaskom/seaborn/blob/master/seaborn/categorical.py#L1890</a></p>
<p dir="auto">IIUC, in order for the area to be  proportional to the percentage of data covered, as documented (<a href="https://github.com/mwaskom/seaborn/blob/master/seaborn/categorical.py#L2672">https://github.com/mwaskom/seaborn/blob/master/seaborn/categorical.py#L2672</a>), the formula should rather be:</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="'area': lambda h, i, k: (1 - 2**(-k + i - 1)) / h}"><pre class="notranslate"><code class="notranslate">'area': lambda h, i, k: (1 - 2**(-k + i - 1)) / h}
</code></pre></div>