擅长:python、mysql、java
<h2>使用<code>shift()</code>代替<code>for looping</code></h2>
<p>在pandas中,应该使用<a href="http://pandas.pydata.org/pandas-docs/stable/generated/pandas.DataFrame.shift.html#pandas-dataframe-shift" rel="nofollow">^{<cd3>}</a>特性而不是<code>for looping</code>。Pandas被构建成对数据列执行这些精确类型的计算,而不必对每一行执行<code>for looping</code>!在</p>
<p>假设您的原始数据在一个名为<code>df</code>的<code>DataFrame</code>中,那么方程将表示为</p>
<pre><code># Calculate equation (broken into numerator and denominator for example)
numerator = df['pt_power_avg [Pi]'] - df['pt_power_avg [Pi]'].shift()
denominator = df['normalized_speed [Vi]'] - df['normalized_speed [Vi]'].shift()
calculated_sensitivity = (numerator / denominator).abs()
# Add to DataFrame
print 'Calculated Sensitivity:'
print calculated_sensitivity
print
</code></pre>
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^{pr2}$