Forgive me, I'm new to Python.
Given a string that starts with a float of indeterminate length and ends with the same, how can I extract both of them into an array, or if there is just one float, just the one.
Example:
"38.00,SALE ,15.20"
"69.99"
I'd like to return:
[38.00, 15.20]
[69.99]
You could also use regex to do this
import re
s = "38.00,SALE ,15.20"
p = re.compile(r'\d+\.\d+') # Compile a pattern to capture float values
floats = [float(i) for i in p.findall(s)] # Convert strings to float
print floats
Output:
[38.0, 15.2]
def extract_nums(text):
for item in text.split(','):
try:
yield float(item)
except ValueError:
pass
print list(extract_nums("38.00,SALE ,15.20"))
print list(extract_nums("69.99"))
[38.0, 15.2]
[69.99]
However by using float conversion you are losing precision, If you want to keep the precision you can use decimal:
import decimal
def extract_nums(text):
for item in text.split(','):
try:
yield decimal.Decimal(item)
except decimal.InvalidOperation:
pass
print list(extract_nums("38.00,SALE ,15.20"))
print list(extract_nums("69.99"))
[Decimal('38.00'), Decimal('15.20')]
[Decimal('69.99')]
csv is overkill for grabbing a couple of floats with known position in a string.
csv, where did you see me using it? Were you reading my mind?import csv hahahaha.You said you're only interested in floats at the start and end of the string, so assuming it's comma-delimited:
items = the_string.split(',')
try:
first = float(items[0])
except (ValueError, IndexError):
pass
try:
second = float(items[-1])
except (ValueError, IndexError):
pass
We have to wrap the operations in exception handlers since the value might not be a valid float (ValueError) or the index might not exist in the list (an IndexError).
This will handle all cases including if one or both of the floats is omitted.
You can try something like
the_string = "38.00,SALE ,15.20"
floats = []
for possible_float in the_string.split(','):
try:
floats.append (float (possible_float.strip())
except:
pass
print floats
for loop if you know beforehand there are only 2 values of interest. Just extract the 2 values from where you know they are.Try a list comprehension:
just_floats = [i for i in your_list.split(',') if i.count('.') == 1]
first you split the string where the commas are, then you filter through the string and get rid of values that don't have a decimal place
import re
map(float, filter(lambda x: re.match("\s*\d+.?\d+\s*", x) , input.split(","))
Input : input = '38.00,SALE ,15.20' Output: [38.0, 15.2]
Input : input = '38.00,SALE ,15.20, 15, 34.' Output: [38.0, 15.2, 15.0, 34.0]
Explanation:
list_to_filter = input.split(",") splits on , filtered_list = filter(<lambda>, list_to_filter) , here item is included in output of filter if lamda expression is true. So when re.match("\s*\d+.?\d+\s*", x) matches for string x filter keeps it. map(float, filtered_list). What it does is apply float() function to each element of the list
Split the input, check if each element is numeric when the period is removed, convert to float if it is.
def to_float(input):
return [float(x) for x in input.split(",") if unicode(x).replace(".", "").isdecimal()]
