Search code examples
pythonmatplotlibseabornlegend

Why doesn't sns.barplot legend show all values?

I have the following graph. Why does the last graph legend not contain all labels? It should contain these values:

[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 20, 21]

enter image description here

Code:

# select only this year
year = 2022
quarter = [1, 2, 3, 4]

# check dataframe (there's no 4 quarter in 2022 year)
def is_df_empty(df):
    return len(df) != 0


# filter by 2022 year
df_year = df4_1_grouped[(df4_1_grouped['date'].dt.year == year)]
# count number of quarters in year
number_of_plots = len(df_year['date'].dt.quarter.unique())
# subplots
figure, axs = plt.subplots(number_of_plots, 1, figsize=(10, 6*number_of_plots))
axes = axs.ravel()

# loop for iter quarters
for q, ax in zip(quarter, axes):
    # filter by quarter
    df_filtered = df_year[
        df_year['date'].dt.quarter.isin(list([q]))
    ]
    # check df.empty
    if is_df_empty(df_filtered):
        # plot
        ax = sns.barplot(
            data=df_filtered,
            x='month_dt',
            y='mentor_cnt',
            hue='sessions',
            ax=ax,
            palette="BrBG",
            linewidth=0
        )
        # add values
        for container in ax.containers:
            ax.bar_label(container, size=11)

        ax.grid(False)
        ax.tick_params(axis='both', labelsize=12)
        ax.set_xlabel('')
        ax.set_ylabel('Mentors', fontsize=14)
        ax.set_ylim(0, max(df_filtered['mentor_cnt'])*1.2)
        # add legend
        ax.legend(loc='upper right', fontsize=11)
        ax.set_title(f'Session finished per month for mentors {year} year - {q} quarter', fontsize=15)

    else:
        continue
plt.tight_layout()
plt.show()

Table:

month_dt sessions mentor_cnt date
37 2022-01-01 1 133 2022-01-01 00:00:00
38 2022-01-01 2 53 2022-01-01 00:00:00
39 2022-01-01 3 18 2022-01-01 00:00:00
40 2022-02-01 1 142 2022-02-01 00:00:00
41 2022-02-01 2 52 2022-02-01 00:00:00
42 2022-02-01 3 18 2022-02-01 00:00:00
43 2022-02-01 4 1 2022-02-01 00:00:00
44 2022-02-01 5 1 2022-02-01 00:00:00
45 2022-03-01 1 164 2022-03-01 00:00:00
46 2022-03-01 2 73 2022-03-01 00:00:00
47 2022-03-01 3 36 2022-03-01 00:00:00
48 2022-03-01 4 7 2022-03-01 00:00:00
49 2022-04-01 1 175 2022-04-01 00:00:00
50 2022-04-01 2 102 2022-04-01 00:00:00
51 2022-04-01 3 39 2022-04-01 00:00:00
52 2022-04-01 4 16 2022-04-01 00:00:00
53 2022-04-01 5 4 2022-04-01 00:00:00
54 2022-04-01 6 2 2022-04-01 00:00:00
55 2022-05-01 1 168 2022-05-01 00:00:00
56 2022-05-01 2 118 2022-05-01 00:00:00
57 2022-05-01 3 45 2022-05-01 00:00:00
58 2022-05-01 4 21 2022-05-01 00:00:00
59 2022-05-01 5 13 2022-05-01 00:00:00
60 2022-05-01 6 2 2022-05-01 00:00:00
61 2022-06-01 1 179 2022-06-01 00:00:00
62 2022-06-01 2 111 2022-06-01 00:00:00
63 2022-06-01 3 52 2022-06-01 00:00:00
64 2022-06-01 4 24 2022-06-01 00:00:00
65 2022-06-01 5 6 2022-06-01 00:00:00
66 2022-06-01 6 9 2022-06-01 00:00:00
67 2022-06-01 7 3 2022-06-01 00:00:00
68 2022-07-01 1 167 2022-07-01 00:00:00
69 2022-07-01 2 129 2022-07-01 00:00:00
70 2022-07-01 3 85 2022-07-01 00:00:00
71 2022-07-01 4 38 2022-07-01 00:00:00
72 2022-07-01 5 16 2022-07-01 00:00:00
73 2022-07-01 6 11 2022-07-01 00:00:00
74 2022-07-01 7 8 2022-07-01 00:00:00
75 2022-07-01 8 1 2022-07-01 00:00:00
76 2022-07-01 9 1 2022-07-01 00:00:00
77 2022-08-01 1 155 2022-08-01 00:00:00
78 2022-08-01 2 123 2022-08-01 00:00:00
79 2022-08-01 3 91 2022-08-01 00:00:00
80 2022-08-01 4 50 2022-08-01 00:00:00
81 2022-08-01 5 34 2022-08-01 00:00:00
82 2022-08-01 6 26 2022-08-01 00:00:00
83 2022-08-01 7 16 2022-08-01 00:00:00
84 2022-08-01 8 8 2022-08-01 00:00:00
85 2022-08-01 9 5 2022-08-01 00:00:00
86 2022-08-01 10 1 2022-08-01 00:00:00
87 2022-08-01 12 1 2022-08-01 00:00:00
88 2022-09-01 1 183 2022-09-01 00:00:00
89 2022-09-01 2 105 2022-09-01 00:00:00
90 2022-09-01 3 65 2022-09-01 00:00:00
91 2022-09-01 4 32 2022-09-01 00:00:00
92 2022-09-01 5 13 2022-09-01 00:00:00
93 2022-09-01 6 12 2022-09-01 00:00:00
94 2022-09-01 7 7 2022-09-01 00:00:00
95 2022-09-01 8 6 2022-09-01 00:00:00
96 2022-09-01 9 2 2022-09-01 00:00:00
97 2022-09-01 10 1 2022-09-01 00:00:00
98 2022-09-01 11 2 2022-09-01 00:00:00
99 2022-09-01 13 1 2022-09-01 00:00:00
100 2022-09-01 20 1 2022-09-01 00:00:00
101 2022-09-01 21 1 2022-09-01 00:00:00
Solution

  • As of seaborn 0.13.0, legend entries will sometimes be hidden by default.

    There is now a legend parameter to control how much is shown:

    legend=... Behavior
    "brief" Numeric hue and size variables will be represented with a sample of evenly spaced values
    "full" Every group will get an entry in the legend
    "auto" (default) Choose between brief or full representation based on number of levels
    False No legend data is added and no legend is drawn

    So use legend="full" if you want to make sure all legend entries are shown:

    ax = sns.barplot(
    data=df_filtered,
    x="month_dt",
    y="mentor_cnt",
    hue="sessions",
    ax=ax,
    palette="BrBG",
    legend="full" # new in seaborn 0.13.0
)

    with full legend