Vorlesung 4

Sonstiges/STAT2/vl2-varianz-v1.py

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+import pandas as pd
+import numpy as np
+
+df = pd.read_csv('/home/pi/Documents/Code/Python/ProgrammierungUndDatenanalyse/Sonstiges/STAT2/vl2-varianz-v1.csv')
+
+# Dataframe
+print(df)
+#    x  freq
+# 0  1  9
+# 1  2  7
+# 2  3  5
+# 3  4  4
+# 4  5  2
+print(df.sum())
+# x    15
+# freq    27
+sums = df.sum()
+print(sums['freq'])
+# 27
+
+# Calculate Mean, respecting frequencies
+rowSum = 0
+for index, row in df.iterrows():
+    rowSum = rowSum + row.x * row.freq
+mean = rowSum / sums.freq
+print("mean: ", mean)
+
+# Calculate Variance, respecting frequencies
+# Sample Variance: ^σ² = (1 / n - 1) * Σ(freq*(x - mean)²)
+variancePart1 = (1 / (sums.freq - 1))
+variancePart2 = 0
+for index, row in df.iterrows():    
+    variancePart2 = variancePart2 + (row.freq * (row.x - mean)**2)
+    print(row['x'], row['freq'], variancePart2)
+variance = variancePart1 * variancePart2
+print("variance: ", variance)
+# variance:  1.703703703703704