I am pulling data from a table that changes often using Python - and the method I am using is not ideal. What I would like to have is a method to pull all strings that contain only one letter and leave out anything that is 2 or more.

An example of data I might get:

115 19A6 HYS8 568

In this example, I would like to pull 115, 19A6, and 568.

Currently I am using the isdigit() method to determine if it is a digit and this filters out all numbers with one letter, which works for some purposes, but is less than ideal.

CodePudding user response：

Try this:

string_list = ["115", "19A6", "HYS8", "568"]
output_list = []

for item in string_list: # goes through the string list
    letter_counter = 0 
    for letter in item: # goes through the letters of one string
        if not letter.isdigit(): # checks if the letter is a digt
            letter_counter  = 1
    if letter_counter < 2: # if the string has more then 1 letter it wont be in output list
        output_list.append(item)

print(output_list)

Output:

['115', '19A6', '568']

CodePudding user response：

Here is a one-liner with a regular expression:

import re

data = ["115", "19A6", "HYS8", "568"]
out = [string for string in data if len(re.sub("\d", "", string))<2]
print(out)

Output:

['115', '19A6', '568']

CodePudding user response：

This is an excellent case for regular expressions (regex), which is available as the built-in re library.

The code below follows the logic:

• Define the dataset.
• Compile a character pattern to be matched. In this case, zero or more digits, followed by zero or one upper case letter, ending with zero of more digits.
• Use the filter function to detect matches in the data list and output as a list.

For example:

import re

data = ['115', '19A6', 'HYS8', '568']
rexp = re.compile('^\d*[A-Z]{0,1}\d*$')
result = list(filter(rexp.match, data))

print(result)

Output:

['115', '19A6', '568']