CODEWITHSUNDEEP
pythonmatplotlibplot
Tuyen
Tuyen

Reputation: 1111

Change color at certain bar labels with barplot in matplotlib

I try to plot a bar graph with certain colors to labels and make legend with color for each type. For example, labels "Type 1", "Type 2" and "Type 3" each color corresponding to each label. Thanks!

import matplotlib.pyplot as plt
import pandas as pd
mdict={"Types":["A","B","C","D","F", "G"],"Count":[3,4,5,6,7,6]}
df=pd.DataFrame(mdict)

fig, ax=plt.subplots(figsize=(15,8))

for i in df.Types:
    if i in ["A","B"]:
        ax.bar(df.Types,df.Count,color="red", label="Type 1")
    elif i in ["C","D"]:
        ax.bar(df.Types,df.Count,color="green", label="Type 2")
    else:
        ax.bar(df.Types,df.Count, color="blue", label="Type 3")
ax.legend()

Upvotes: 0

Views: 2210

Answers (1)

JohanC
JohanC

Reputation: 80574

You could add an extra column for the labels, and use seaborn to create the plot:

import matplotlib.pyplot as plt
import seaborn as sns
import pandas as pd

mdict = {"Types": ["A", "B", "C", "D", "F", "G"], "Count": [3, 4, 5, 6, 7, 6]}
df = pd.DataFrame(mdict)

df["Label"] = "Type 3"
df.loc[df["Types"].isin(["A", "B"]), "Label"] = "Type 1"
df.loc[df["Types"].isin(["C", "D"]), "Label"] = "Type 2"

fig, ax = plt.subplots(figsize=(15, 8))
palette = {"Type 1": "crimson", "Type 2": "limegreen", "Type 3": "dodgerblue"}
sns.barplot(data=df, x="Types", y="Count", hue="Label", palette=palette, dodge=False, ax=ax)
plt.show()

sns.barplot colored via type

An alternative approach, without seaborn, creates two columns: one for labels and one for a numeric index. Recent matplotlib versions accept a data= keyword, to indicate a dataframe (or a subset of a dataframe). A numeric index is needed to draw the bars at the correct positions.

import matplotlib.pyplot as plt
import pandas as pd

mdict = {"Types": ["A", "B", "C", "D", "F", "G"], "Count": [3, 4, 5, 6, 7, 6]}
df = pd.DataFrame(mdict)

df["Label"] = ["Type 1" if i in ["A", "B"] else "Type 2" if i in ["C", "D"] else "Type 3" for i in df["Types"]]
df["ind"] = range(len(df))

fig, ax = plt.subplots(figsize=(15, 8))
ax.bar("ind", "Count", color="crimson", label="Type 1",
       data=df.loc[df["Types"].isin(["A", "B"])])
ax.bar("ind", "Count", color="limegreen", label="Type 2",
       data=df.loc[df["Types"].isin(["C", "D"])])
ax.bar("ind", "Count", color="dodgerblue", label="Type 2",
       data=df.loc[~ (df["Types"].isin(["A", "B"]) | df["Types"].isin(["C", "D"]))])
ax.set_xticks(df["ind"], df["Types"])
ax.legend()
plt.show()

Upvotes: 2

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