(Program 4-10) Consider the open dataset "Seasonal and Annual Min/Max Temp Series - India from 1901 to 2017" from data.gov.in (file "Min_Max_Seasonal_IMD_2017.csv"). The aim is to plot the minimum and maximum temperature and observe the number of times (frequency) a particular te

Question

(Program 4-10) Consider the open dataset "Seasonal and Annual Min/Max Temp Series - India from 1901 to 2017" from data.gov.in (file "Min_Max_Seasonal_IMD_2017.csv"). The aim is to plot the minimum and maximum temperature and observe the number of times (frequency) a particular temperature has occurred. Extract only the 'ANNUAL - MIN' and 'ANNUAL - MAX' columns from the file and display two Histogram plots: (i) only for 'ANNUAL - MIN' (ii) for both 'ANNUAL - MIN' and 'ANNUAL - MAX' (with x axis labelled 'Temperature' and y axis 'Number of times').

Accepted Answer

> [!TLDR]
> Read only the two temperature columns needed, then plot each as its own histogram.

```python
import pandas as pd
import matplotlib.pyplot as plt
data=pd.read_csv("Min_Max_Seasonal_IMD_2017.csv", usecols=['ANNUAL - MIN','ANNUAL - MAX'])
df=pd.DataFrame(data)
df.plot(kind='hist',y='ANNUAL - MIN',title='Annual Minimum Temperature (1901-2017)')
plt.xlabel('Temperature')
plt.ylabel('Number of times')
df.plot(kind='hist',title='Annual Min and Max Temperature (1901-2017)',color=['blue','red'])
plt.xlabel('Temperature')
plt.ylabel('Number of times')
plt.show()
```

`usecols=[...]` at read time keeps only the two needed columns; `df.plot(kind='hist', ...)` builds the histogram directly, without arbitrary manual bin counts.

### Step by step
1. `usecols=['ANNUAL - MIN','ANNUAL - MAX']` filters the columns AT READ TIME, so
   pandas never even loads the dataset's other seasonal columns (JAN-FEB, MAR-MAY,
   etc.) into memory -- useful since the real IMD file spans 1901-2017, a long
   time series with many columns this question doesn't need.
2. The first `df.plot(kind='hist', y='ANNUAL - MIN', ...)` call restricts the plot …

Concept understanding — Histogram Visualization

Histogram Visualization

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