(Program 4-11) Plot a frequency polygon for the 'ANNUAL - MIN' column of the "Min/Max Temp" data (file "Min_Max_Seasonal_IMD_2017.csv") over the histogram depicting it.

Question

Accepted Answer

> [!TLDR]
> Overlay a frequency-polygon line on the minimum-temperature histogram using NumPy's own histogram function.

```python
import numpy as np
import pandas as pd
import matplotlib.pyplot as plt
data=pd.read_csv("Min_Max_Seasonal_IMD_2017.csv", usecols=['ANNUAL - MIN'])
df=pd.DataFrame(data)
minarray=np.array([df['ANNUAL - MIN']])
y,edges = np.histogram(minarray)
mid = 0.5*(edges[1:]+edges[:-1])
df.plot(kind='hist',y='ANNUAL - MIN')
plt.plot(mid,y,'-^')
plt.title('Annual Min Temperature plot(1901 - 2017)')
plt.xlabel('Temperature')
plt.show()
```

`np.histogram()` computes the same bin counts/edges the histogram will use; `mid` (the midpoint of each bin) lets a line with triangle markers ('-^') be overlaid on the bars at their true centre points.

### Step by step
1. `np.histogram(minarray)` computes the SAME bin edges and counts a histogram bar
   chart would show, but returns them as plain numbers (`y` = counts, `edges` = the
   10 bin boundaries) instead of drawing bars.
2. `mid = 0.5*(edges[1:]+edges[:-1])` finds the midpoint of every bin -- the natural
   x-position to place a point representing "this bin's count".
3. `df.plot(kind='hist', ...)` draws the ordinary histogram bars first. …

Q.(Program 4-11) Plot a frequency polygon for the 'ANNUAL - MIN' column of the "Min/Max Temp" data (file "Min_Max_Seasonal_IMD_2017.csv") over the histogram depicting it.

Concept understanding — Histogram Visualization

Histogram Visualization

Why the shape matters

What it reveals that raw numbers hide

Step by step

Q.(Program 4-11) Plot a frequency polygon for the 'ANNUAL - MIN' column of the "Min/Max Temp" data (file "Min_Max_Seasonal_IMD_2017.csv") over the histogram depicting it.

Step by step

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