CODEWITHSUNDEEP
pythonarraysnumpy
DarkSky
DarkSky

Reputation: 45

python conversion of two dimensional list of float to two dimensional array of float

I am trying to read a column of float into a list for each of a set of CSV files, then appending to a two dimensional list, later converting that to a 2D array, but the array doesn't convert into a two dimensional array of float (paraphrased below). Where am I going wrong?

import numpy
symbols = ['CVX', 'COP', 'MMM', 'BP', 'HMC', 'TM']
AA_lst = []
nSyms = len(symbols)
shortest = 99999
for sym in symbols
    fn = "PricesOf_" + sym + ".csv"
    col = getCSVcolumn( fn, "Close" )
    print( "type(col)="    + str(type(col)) )     # --> <class 'list'>
    print( "type(col[0])=" + str(type(col[0])) )  # --> <class 'float'>
    shortest = min(shortest,len(col))
    AA_lst.append(col)                            # appended as a row of AA_lst

AA = numpy.array( AA_lst )
print( "type=(AA)="     + str(type(AA)) )         # --> <class 'numpy.ndarray'>
print( "type=(AA[0]="   + str(type(AA[0])) )      # --> <class 'list'>
#print( "type=(AA[0,0]=" + str(type(AA[0,0])) )   # --> Error, too many indices

# fix up dimensions (so rows are all the same length)
AA = numpy.resize( AA, (nSyms, shortest) )
print( "type=(AA)="     + str(type(AA)) )         # --> <class 'numpy.ndarray'>
print( "type=(AA[0]="   + str(type(AA[0])) )      # --> <class 'numpy.ndarray'>
print( "type=(AA[0,0]=" + str(type(AA[0,0])) )    # --> <class 'list'>

# desire something of the form:  array([[1,2,3] [4,5,6] [7,8,9]])
# i.e. expecting type(AA[0,0] to be <class 'float'>, not <class 'list'>

Upvotes: 0

Views: 408

Answers (2)

DarkSky
DarkSky

Reputation: 45

Problem solved by replacing numpy.resize(...) with:

AAA_lst = []
for row in AA_lst:
    AAA_lst.append( row[:shortestUnshifted] )

and feeding AAA_lst to numpy.array()

Upvotes: 1

Yariv
Yariv

Reputation: 13321

  1. Make sure the lists in AA_lst are of the same length.
  2. Consider using pandas.

Upvotes: 1

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