我正在寻找一个函数,它将两个列表作为输入,并返回Pearson相关性,以及相关性的重要性。
当前回答
您可能想知道如何在寻找特定方向的相关性(负相关或正相关)的上下文中解释您的概率。这是我写的一个函数。它甚至可能是正确的!
这是基于我从http://www.vassarstats.net/rsig.html和http://en.wikipedia.org/wiki/Student%27s_t_distribution上收集到的信息,感谢这里发布的其他答案。
# Given (possibly random) variables, X and Y, and a correlation direction,
# returns:
# (r, p),
# where r is the Pearson correlation coefficient, and p is the probability
# that there is no correlation in the given direction.
#
# direction:
# if positive, p is the probability that there is no positive correlation in
# the population sampled by X and Y
# if negative, p is the probability that there is no negative correlation
# if 0, p is the probability that there is no correlation in either direction
def probabilityNotCorrelated(X, Y, direction=0):
x = len(X)
if x != len(Y):
raise ValueError("variables not same len: " + str(x) + ", and " + \
str(len(Y)))
if x < 6:
raise ValueError("must have at least 6 samples, but have " + str(x))
(corr, prb_2_tail) = stats.pearsonr(X, Y)
if not direction:
return (corr, prb_2_tail)
prb_1_tail = prb_2_tail / 2
if corr * direction > 0:
return (corr, prb_1_tail)
return (corr, 1 - prb_1_tail)
其他回答
您可能想知道如何在寻找特定方向的相关性(负相关或正相关)的上下文中解释您的概率。这是我写的一个函数。它甚至可能是正确的!
这是基于我从http://www.vassarstats.net/rsig.html和http://en.wikipedia.org/wiki/Student%27s_t_distribution上收集到的信息,感谢这里发布的其他答案。
# Given (possibly random) variables, X and Y, and a correlation direction,
# returns:
# (r, p),
# where r is the Pearson correlation coefficient, and p is the probability
# that there is no correlation in the given direction.
#
# direction:
# if positive, p is the probability that there is no positive correlation in
# the population sampled by X and Y
# if negative, p is the probability that there is no negative correlation
# if 0, p is the probability that there is no correlation in either direction
def probabilityNotCorrelated(X, Y, direction=0):
x = len(X)
if x != len(Y):
raise ValueError("variables not same len: " + str(x) + ", and " + \
str(len(Y)))
if x < 6:
raise ValueError("must have at least 6 samples, but have " + str(x))
(corr, prb_2_tail) = stats.pearsonr(X, Y)
if not direction:
return (corr, prb_2_tail)
prb_1_tail = prb_2_tail / 2
if corr * direction > 0:
return (corr, prb_1_tail)
return (corr, 1 - prb_1_tail)
嗯,很多回复的代码都很长,很难读…
我建议在处理数组时使用numpy及其漂亮的特性:
import numpy as np
def pcc(X, Y):
''' Compute Pearson Correlation Coefficient. '''
# Normalise X and Y
X -= X.mean(0)
Y -= Y.mean(0)
# Standardise X and Y
X /= X.std(0)
Y /= Y.std(0)
# Compute mean product
return np.mean(X*Y)
# Using it on a random example
from random import random
X = np.array([random() for x in xrange(100)])
Y = np.array([random() for x in xrange(100)])
pcc(X, Y)
Pearson coefficient calculation using pandas in python: I would suggest trying this approach since your data contains lists. It will be easy to interact with your data and manipulate it from the console since you can visualise your data structure and update it as you wish. You can also export the data set and save it and add new data out of the python console for later analysis. This code is simpler and contains less lines of code. I am assuming you need a few quick lines of code to screen your data for further analysis
例子:
data = {'list 1':[2,4,6,8],'list 2':[4,16,36,64]}
import pandas as pd #To Convert your lists to pandas data frames convert your lists into pandas dataframes
df = pd.DataFrame(data, columns = ['list 1','list 2'])
from scipy import stats # For in-built method to get PCC
pearson_coef, p_value = stats.pearsonr(df["list 1"], df["list 2"]) #define the columns to perform calculations on
print("Pearson Correlation Coefficient: ", pearson_coef, "and a P-value of:", p_value) # Results
但是,在分析之前,你没有发布你的数据给我看数据集的大小或可能需要的转换。
下面是mkh答案的一个变体,比它运行得快得多,还有scipy.stats。皮尔逊,使用numba。
import numba
@numba.jit
def corr(data1, data2):
M = data1.size
sum1 = 0.
sum2 = 0.
for i in range(M):
sum1 += data1[i]
sum2 += data2[i]
mean1 = sum1 / M
mean2 = sum2 / M
var_sum1 = 0.
var_sum2 = 0.
cross_sum = 0.
for i in range(M):
var_sum1 += (data1[i] - mean1) ** 2
var_sum2 += (data2[i] - mean2) ** 2
cross_sum += (data1[i] * data2[i])
std1 = (var_sum1 / M) ** .5
std2 = (var_sum2 / M) ** .5
cross_mean = cross_sum / M
return (cross_mean - mean1 * mean2) / (std1 * std2)
一个替代方法可以是一个来自linreturn的本地scipy函数,它计算:
斜率:回归线的斜率 截距:回归线的截距 R-value:相关系数 p值:零假设为斜率为零的假设检验的双面p值 stderr:估计的标准错误
这里有一个例子:
a = [15, 12, 8, 8, 7, 7, 7, 6, 5, 3]
b = [10, 25, 17, 11, 13, 17, 20, 13, 9, 15]
from scipy.stats import linregress
linregress(a, b)
会回复你:
LinregressResult(slope=0.20833333333333337, intercept=13.375, rvalue=0.14499815458068521, pvalue=0.68940144811669501, stderr=0.50261704627083648)