[英]Pandas plot density plot from frequency table
Let's say I have a DataFrame that looks (simplified) like this 假设我有一个看起来像这样(简化)的DataFrame
>>> df
freq
2 2
3 16
1 25
where the index column represents a value, and the freq
column represents the frequency of occurance of that value, as in a frequency table. 其中的index列代表一个值,而
freq
列代表该值的出现频率,如频率表中所示。
I'd like to plot a density plot for this table like one obtained from plot kind kde
. 我想为此表绘制一个密度图,就像从图类型
kde
获得的密度图一样。 However, this kind is apparently only meant for pd.Series
. 但是,这种类型显然仅适用于
pd.Series
。 My df
is too large to flatten out to a 1D Series, ie df = [2, 2, 3, 3, 3, ..,, 1, 1]
. 我的
df
太大,无法展平为1D系列,即df = [2, 2, 3, 3, 3, ..,, 1, 1]
。 How can I plot such a density plot under these circumstances? 在这种情况下如何绘制密度图?
I know you have asked for the case where df
is too large to flatten out, but the following answer works where this isn't the case: 我知道您已经问过
df
太大而无法展平的情况,但是以下回答适用于这种情况:
pd.Series(df.index.repeat(df.freq)).plot.kde()
Or more generally, when the values are in a column called val
and not the index: 或更一般而言,当值位于名为
val
而不是索引的列中时:
df.val.repeat(df.freq).plot.kde()
You can plot a density distribution using a bar plot if you normalize the y values by the product of the size of the population. 如果您通过总体大小的乘积对y值进行归一化,则可以使用条形图来绘制密度分布。 This will make the area covered by the bars equal to 1.
这将使条形图覆盖的面积等于1。
plt.bar(
df.index,
df.freq / df.freq.sum(),
width=-1,
align='edge'
)
The width
and align
parameters are to make sure each bar covers the interval (k-1, k]. width
和align
参数应确保每个条形都覆盖间隔(k-1,k]。
Somebody with better knowledge of statistics should answer whether kernel density estimation actually makes sense for discrete distributions. 了解统计信息的人应该回答内核密度估计对于离散分布是否真正有意义。
Maybe this will work: 也许这可以工作:
import matplotlib.pyplot as plt
plt.plot(df.index, df['freq'])
plt.show()
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