pyspark 如何得到一个Spark Dataframe 的相关矩阵?

kb5ga3dv  于 2023-01-20  发布在  Spark
关注(0)|答案(4)|浏览(217)

我有一个很大的pyspark数据框。我想得到它的相关矩阵。我知道如何用Pandas数据框得到它。但是我的数据太大了,无法转换成Pandas。所以我需要用pyspark数据框得到结果。我搜索了其他类似的问题,答案对我不起作用。有人能帮助我吗?谢谢!
数据示例:data example

dluptydi

dluptydi1#

欢迎您来到中国!

示例数据

我准备了一些虚拟数据以便于复制(也许下次您也可以提供一些易于复制的数据;-)):

data = pd.DataFrame(np.random.random((10, 5)), 
                   columns=["x{}".format(x) for x in range(5)])
df = spark.createDataFrame(data)

df.show()

下面是数据:

+-------------------+-------------------+-------------------+-------------------+--------------------+
|                 x0|                 x1|                 x2|                 x3|                  x4|
+-------------------+-------------------+-------------------+-------------------+--------------------+
| 0.9965335347601945|0.09311299224360992| 0.9273393764180728| 0.8523333283310564|  0.5040716744686445|
| 0.2341313103221958| 0.9356109544246494| 0.6377089480113576| 0.8129047787928055| 0.22215891357547046|
| 0.6310473705907303| 0.2040705293700683|0.17329601185489396| 0.9062007987480959| 0.44105687572209895|
|0.27711903958232764| 0.9434521502343274| 0.9300724702792151| 0.9916836130997986|  0.6869145183972896|
| 0.8247010263098201| 0.6029990758603708|0.07266306799434707| 0.6808038838294564| 0.27937146479120245|
| 0.7786370627473335|0.17583334607075107| 0.8467715537463528|   0.67702427694934|  0.8976402177586831|
|0.40620117097757724| 0.5080531043890719| 0.3722402520743703|0.14555317396545808|  0.7954133091360741|
|0.20876805543974553| 0.9755867281355178| 0.7570617946515066| 0.6974893162590945|0.054708580878511825|
|0.47979629269402546| 0.1851379589735923| 0.4786682088989791| 0.6809358266732168|  0.8829180507209633|
| 0.1122983875801804|0.45310988757198734| 0.4713203140134805|0.45333792855503807|  0.9189083355172629|
+-------------------+-------------------+-------------------+-------------------+--------------------+

溶液

ml子包pyspark.ml.stat中有一个correlation函数,但是它要求您提供一个类型为Vector的列,因此您需要先使用VectorAssembler将列转换为向量列,然后应用correlation:

from pyspark.ml.stat import Correlation
from pyspark.ml.feature import VectorAssembler

# convert to vector column first
vector_col = "corr_features"
assembler = VectorAssembler(inputCols=df.columns, outputCol=vector_col)
df_vector = assembler.transform(df).select(vector_col)

# get correlation matrix
matrix = Correlation.corr(df_vector, vector_col)

如果你想得到一个numpy数组的结果(在你的驱动程序上),你可以使用以下代码:

matrix.collect()[0]["pearson({})".format(vector_col)].values

array([ 1.        , -0.66882741, -0.06459055,  0.21802534,  0.00113399,
       -0.66882741,  1.        ,  0.14854203,  0.09711389, -0.5408654 ,
       -0.06459055,  0.14854203,  1.        ,  0.33513733,  0.09001684,
        0.21802534,  0.09711389,  0.33513733,  1.        , -0.37871581,
        0.00113399, -0.5408654 ,  0.09001684, -0.37871581,  1.        ])
tzcvj98z

tzcvj98z2#

基于@pansen的答案,但****为了更好地可视化结果,您还可以使用...
1.易于可视化

matrix = Correlation.corr(df_vector, 'corr_vector').collect()[0][0] 
corr_matrix = matrix.toArray().tolist() 
corr_matrix_df = pd.DataFrame(data=corr_matrix, columns = numeric_variables, index=numeric_variables) 
corr_matrix_df .style.background_gradient(cmap='coolwarm').set_precision(2)

2.更好的可视化

import seaborn as sns 
import matplotlib.pyplot as plt

plt.figure(figsize=(16,5))  
sns.heatmap(corr_matrix_df, 
            xticklabels=corr_matrix_df.columns.values,
            yticklabels=corr_matrix_df.columns.values,  cmap="Greens", annot=True)

jxct1oxe

jxct1oxe3#

更清晰:

from pyspark.ml.stat import Correlation
from pyspark.ml.feature import VectorAssembler

# convert to vector column first
vector_col = "corr_features"
assembler = VectorAssembler(inputCols=df.columns, outputCol=vector_col)
df_vector = assembler.transform(df).select(vector_col)
matrix = Correlation.corr(df_vector, vector_col)
cor_np = matrix.collect()[0][matrix.columns[0]].toArray()
fumotvh3

fumotvh34#

下面是@Artur的一个情节复杂的版本:

import numpy as np
import plotly.graph_objects as go

matrix = Correlation.corr(df_vector, vector_col).collect()[0][0].toArray()

# to only show one triangle
m = matrix
m[np.triu_indices(m.shape[0], 0)] = None

corr_matrix = m.tolist() 
corr_matrix_df = pd.DataFrame(data=corr_matrix, columns = numeric_columns, index=numeric_columns) 

labels = corr_matrix_df.columns.values
fig = go.Figure(data=go.Heatmap(
                    z=corr_matrix_df,
                    x = labels,
                    y = labels, 
                    text=corr_matrix_df.round(2),
                    texttemplate="%{text}",
                    textfont={"size":8},
                    colorscale='greens'
                    )
                )
fig.update_xaxes(showticklabels=False)
fig.update_yaxes(autorange="reversed")

fig.show()

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