Why Data Visualization?Data ko sirf table me dekhne se pattern samajh nahi aata. Graphs se hum 1 min me trend, outlier, correlation pakad lete hain.
Key Goals:
- Explore: Data me kya chal raha hai samjhna
- Explain: Result dusro ko dikhana
- Detect: Outliers, missing values, distribution
2.Types of Charts & Kab Use Karein
| Chart Type | Use Case | Python Library |
| Bar Chart | Categories compare karna | matplotlib.pyplot.bar() |
| Line Chart | Time series trend | plt.plot() |
| Histogram | Data ka distribution | plt.hist() |
| Scatter Plot | 2 variables ka relation | plt.scatter() |
| Box Plot | Outliers + Quartiles | sns.boxplot() |
| Heatmap | Correlation matrix | sns.heatmap() |
| Pie Chart Percentage | compositionplt.pie() |
3.Important Python Libraries
import matplotlib.pyplot as plt # Basic plots
import seaborn as sns # Better looking plots
import plotly.express as px # Interactive plots
import pandas as pd
4. IMPO Programs for Chapter 5
Program 1: Bar Chart
import matplotlib.pyplot as plt
subjects = [‘Python’, ‘SQL’, ‘ML’, ‘Stats’]
scores = [90, 80, 85, 75]
plt.bar(subjects, scores, color=’skyblue’)
plt.title(“Gatestudy Student Scores”)
plt.show()
Program 2: Histogram – Data Distribution
import seaborn as sns
data = [12, 15, 18, 20, 20, 22, 25, 30, 35]
sns.histplot(data, bins=5, kde=True)
plt.title(“Age Distribution”)
Program 3: Scatter Plot – Correlation
import matplotlib.pyplot as plt
study_hours = [1, 2, 3, 4, 5]
marks = [40, 50, 60, 70, 90]
plt.scatter(study_hours, marks)
plt.xlabel(“Study Hours”); plt.ylabel(“Marks”)
plt.show()
Program 4: Heatmap – Correlation
import seaborn as sns
import pandas as pd
df = pd.DataFrame({‘A’:[1,2,3], ‘B’:[3,2,1], ‘C’:[1,1,2]})
sns.heatmap(df.corr(), annot=True, cmap=”YlGnBu”)
Program 5: Box Plot – Outlier Detection
import seaborn as sns
data = [10,12,12,13,14,15,100] # 100 is outlier
sns.boxplot(data=data)
6.Interview/Gate PYQ Type Questions
1-plt.hist() aur sns.histplot() me kya difference hai?
2-Correlation dekhne ke liye kaunsa chart best hai?
3-Overplotting ko kaise handle karenge scatter plot me?
4-Categorical data ke liye kaunsa plot?