tikzplotlib should have a legend for seaborn

[JasonGross]

import matplotlib.pyplot as plt
import seaborn as sns
import tikzplotlib
import numpy as np
np.random.seed(42)
data = np.random.rand(4, 2)
fig, ax = plt.subplots()
sns.scatterplot({str(i): d for i, d in enumerate(data)}, ax=ax)
print(tikzplotlib.get_tikz_code(fig))
plt.close(fig)
fig, ax = plt.subplots()
for i, d in enumerate(data):
    x = range(len(d))
    plt.scatter(x, d, label=str(i))
plt.legend()
# plt.show()
print(tikzplotlib.get_tikz_code(fig))
plt.close(fig)

gives

% This file was created with tikzplotlib v0.10.1.
\begin{tikzpicture}

\definecolor{darkgray176}{RGB}{176,176,176}
\definecolor{lightgray204}{RGB}{204,204,204}

\begin{axis}[
legend cell align={left},
legend style={
  fill opacity=0.8,
  draw opacity=1,
  text opacity=1,
  at={(0.03,0.97)},
  anchor=north west,
  draw=lightgray204
},
tick align=outside,
tick pos=left,
x grid style={darkgray176},
xmin=-0.05, xmax=1.05,
xtick style={color=black},
y grid style={darkgray176},
ymin=0.0134520774561136, ymax=0.995345841122002,
ytick style={color=black}
]
\addplot [
  draw=white,
  forget plot,
  mark=*,
  only marks,
  scatter,
  scatter/@post marker code/.code={%
  \endscope
},
  scatter/@pre marker code/.code={%
  \expanded{%
  \noexpand\definecolor{thispointfillcolor}{RGB}{\fillcolor}%
  }%
  \scope[fill=thispointfillcolor]%
},
  visualization depends on={value \thisrow{fill} \as \fillcolor}
]
table{%
x  y  fill
0 0.374540118847362 31,119,180
1 0.950714306409916 31,119,180
0 0.731993941811405 255,127,14
1 0.598658484197037 255,127,14
0 0.156018640442437 44,160,44
1 0.155994520336203 44,160,44
0 0.0580836121681995 214,39,40
1 0.866176145774935 214,39,40
};
\end{axis}

\end{tikzpicture}

% This file was created with tikzplotlib v0.10.1.
\begin{tikzpicture}

\definecolor{crimson2143940}{RGB}{214,39,40}
\definecolor{darkgray176}{RGB}{176,176,176}
\definecolor{darkorange25512714}{RGB}{255,127,14}
\definecolor{forestgreen4416044}{RGB}{44,160,44}
\definecolor{lightgray204}{RGB}{204,204,204}
\definecolor{steelblue31119180}{RGB}{31,119,180}

\begin{axis}[
legend cell align={left},
legend style={
  fill opacity=0.8,
  draw opacity=1,
  text opacity=1,
  at={(0.03,0.97)},
  anchor=north west,
  draw=lightgray204
},
tick align=outside,
tick pos=left,
x grid style={darkgray176},
xmin=-0.05, xmax=1.05,
xtick style={color=black},
y grid style={darkgray176},
ymin=0.0134520774561136, ymax=0.995345841122002,
ytick style={color=black}
]
\addplot [draw=steelblue31119180, fill=steelblue31119180, mark=*, only marks]
table{%
x  y
0 0.374540118847362
1 0.950714306409916
};
\addlegendentry{0}
\addplot [draw=darkorange25512714, fill=darkorange25512714, mark=*, only marks]
table{%
x  y
0 0.731993941811405
1 0.598658484197037
};
\addlegendentry{1}
\addplot [draw=forestgreen4416044, fill=forestgreen4416044, mark=*, only marks]
table{%
x  y
0 0.156018640442437
1 0.155994520336203
};
\addlegendentry{2}
\addplot [draw=crimson2143940, fill=crimson2143940, mark=*, only marks]
table{%
x  y
0 0.0580836121681995
1 0.866176145774935
};
\addlegendentry{3}
\end{axis}

\end{tikzpicture}

Note that the second one has a legend but the first does not. This is because

tikzplotlib/src/tikzplotlib/_util.py

Line 20 in 450712b

if label in d:

fails, because the single line collection is labeled _child0 instead of having a series label