How to check for numeric values in list of lists and return multiple lists?-CodePudding

I have a list of lists as shown below, my goal is to get the numeric values from it. But the resultant output should be in similar format as of original list. so for example my list looks like this:

a_list = [['49', 'XT', '19.0', '93'],
 ['YTX', '124.0', '167 ', '77.0'],
 ['4 ', 'Y', '128,', '125,'],
 ['142.0', '120', '141.0'],
 ['12 ', '51.0'],
 ['0,', ' 82', '156'],
 ['82', '102.0'],
 ['94', 'YYZ', '178.0', '72'],
 ['120', 'YXT', '142', ' 134'],
 ['45,', '46', '79.0']]

My desired output is

b_list = [['49', '19.0', '93'],
 ['124.0', '167 ', '77.0'],
 ['4 ', '128,', '125,'],
 ['142.0', '120', '141.0'],
 ['12 ', '51.0'],
 ['0,', ' 82', '156'],
 ['82', '102.0'],
 ['94', '178.0', '72'],
 ['120', '142', ' 134'],
 ['45,', '46', '79.0']]

I wrote following code but it skips a lot of numbers plus format is not the same

final=[]
for i in a_list:
    for num in i:
        if num.isdigit():
            final.append(num)

what I am doing wrong? and any way it could be done using list comprehension?

CodePudding user response：

a simple regex solition:

import re
isnum = re.compile(r'\d (\.\d )?$')

final=[]
for i in a_list:
    tmp =[]
    for num in i:
        num = num.strip().replace(",","")
        if isnum.match(num):
            tmp.append(num)
    final.append(tmp)

CodePudding user response：

Try this:

final=[]
for i in a_list:
    for num in i:
        tmp=[]
        if num.isdigit():
            tmp.append(num)
    final.append(tmp)

CodePudding user response：

Your input list sometimes contains characters that will fail the is.decimal check. Define a filtering method and pass it to the filter builtin.

def _method(x):
    y = x.strip().replace('.', '').replace(',', '')
    return y.isdecimal()

result = [list(filter(_method, x)) for x in a_list]

There exists a small catch when it comes to str.isidigit method, for example it will acccept characters like "³" and these cannot be passed as an index to Indexable objects. str.isdecimal is stricter and as far as I know everything that passes through str.isdecimal can be used as an index:

>>> a = '³'
>>> a.isdigit()
True
>>> a.isdecimal()
False

CodePudding user response：

Here is one solution I got:

b_list = []
for i in a_list:
    new_list = []
    for j in i:
        if j.replace(".", "", 1).replace(" ", "", 1).replace(",", "", 1).isdigit():
            new_list.append(j)
    b_list.append(new_list)
b_list

The output is same as your desired output:

[['49', '19.0', '93'],
 ['124.0', '167 ', '77.0'],
 ['4 ', '128,', '125,'],
 ['142.0', '120', '141.0'],
 ['12 ', '51.0'],
 ['0,', ' 82', '156'],
 ['82', '102.0'],
 ['94', '178.0', '72'],
 ['120', '142', ' 134'],
 ['45,', '46', '79.0']]