Problem in defining multidimensional array matrix and regression

[Peter Otten]

shalu.ashu50 at gmail.com wrote:

> Hi, All,
> 
> I have 6 variables in CSV file. One is rainfall (dependent, at y-axis) and
> others are predictors (at x). I want to do multiple regression and create
> a correlation matrix between rainfall (y) and predictors (x; n1=5). Thus I
> want to read rainfall as a separate variable and others in separate
> columns, so I can apply the algo. However, I am not able to make a proper
> matrix for them.
> 
> Here are my data and codes?
> Please suggest me for the same.
> I am new to Python.
> 
> RF	P1	P2	P3	P4	P5
> 120.235	0.234	-0.012	0.145	21.023	0.233
> 200.14	0.512	-0.021	0.214	22.21	0.332
> 185.362	0.147	-0.32	0.136	24.65	0.423
> 201.895	0.002	-0.12	0.217	30.25	0.325
> 165.235	0.256	0.001	0.22	31.245	0.552
> 198.236	0.012	-0.362	0.215	32.25	0.333
> 350.263	0.98	-0.85	0.321	38.412	0.411
> 145.25	0.046	-0.36	0.147	39.256	0.872
> 198.654	0.65	-0.45	0.224	40.235	0.652
> 245.214	0.47	-0.325	0.311	26.356	0.632
> 214.02	0.18	-0.012	0.242	22.01	0.745
> 147.256	0.652	-0.785	0.311	18.256	0.924
> 
> import numpy as np
> import statsmodels as sm
> import statsmodels.formula as smf
> import csv
> 
> with open("pcp1.csv", "r") as csvfile:
>     readCSV=csv.reader(csvfile)
>     
>     rainfall = []
>     csvFileList = []
>     
>     for row in readCSV:
>         Rain = row[0]
>         rainfall.append(Rain)
> 
>         if len (row) !=0:
>             csvFileList = csvFileList + [row]
>         
> print(csvFileList)
> print(rainfall)

You are not the first to read tabular data from a file; therefore numpy (and 
pandas) offer highlevel function to do just that. Once you have the complete 
table extracting a specific column is easy. For instance:

$ cat rainfall.txt 
RF      P1      P2      P3      P4      P5
120.235 0.234   -0.012  0.145   21.023  0.233
200.14  0.512   -0.021  0.214   22.21   0.332
185.362 0.147   -0.32   0.136   24.65   0.423
201.895 0.002   -0.12   0.217   30.25   0.325
165.235 0.256   0.001   0.22    31.245  0.552
198.236 0.012   -0.362  0.215   32.25   0.333
350.263 0.98    -0.85   0.321   38.412  0.411
145.25  0.046   -0.36   0.147   39.256  0.872
198.654 0.65    -0.45   0.224   40.235  0.652
245.214 0.47    -0.325  0.311   26.356  0.632
214.02  0.18    -0.012  0.242   22.01   0.745
147.256 0.652   -0.785  0.311   18.256  0.924
$ python3
Python 3.4.3 (default, Nov 17 2016, 01:08:31) 
[GCC 4.8.4] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import numpy
>>> rf = numpy.genfromtxt("rainfall.txt", names=True)
>>> rf["RF"]
array([ 120.235,  200.14 ,  185.362,  201.895,  165.235,  198.236,
        350.263,  145.25 ,  198.654,  245.214,  214.02 ,  147.256])
>>> rf["P3"]
array([ 0.145,  0.214,  0.136,  0.217,  0.22 ,  0.215,  0.321,  0.147,
        0.224,  0.311,  0.242,  0.311])