Which method returns the next integer greater than or equal to a given number?
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When our Python program works with numerical values, every so often we have turn values with a fractional component into whole (integer) numbers. But how to do so? And what options does Python have? Let’s find out together. Show
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# Round numerical values up and down in PythonWhen we round values, we go from a numerical value with decimal places to a whole number. With this process we do lose some precision, but the rounded value is often much easier to read and interpret. Python has three ways to turn a floating-point value into a whole (integer) number:
If you just want a string or script output with a whole number, then a Python format string can perform that task too. That way you also don’t lose precision in the original value. Let’s see how these three approaches work. # Round values up and down: Python’s # Some numbers to round valueA = 3.14159265359 valueB = 1845.7409947 valueC = -100.95 valueD = 9.5432 valueE = 34.49953 # Round values to whole numbers roundA = round(valueA) roundB = round(valueB) roundC = round(valueC) roundD = round(valueD) roundE = round(valueE) # Output rounded values print("Value:".ljust(15), "Rounded:") print(str(valueA).ljust(15), roundA) print(str(valueB).ljust(15), roundB) print(str(valueC).ljust(15), roundC) print(str(valueD).ljust(15), roundD) print(str(valueE).ljust(15), roundE) 5 functionTo round floating-point values up and down we use Python’s To do that latter, we call The For instance, both When we give # Example: round Python numbers to the nearest full integerTo see how the Here we first make five variables with floating-point values. Some have a lot of decimal places and others just a few. Then we do some rounding. For that we call the Next we output the results with the Here’s how the rounded values look: FURTHER READING
# Round down to the next integer: Python’s # Some numbers to round valueA = 3.14159265359 valueB = 1845.7409947 valueC = -100.95 valueD = 9.5432 valueE = 34.49953 # Round values to whole numbers roundA = round(valueA) roundB = round(valueB) roundC = round(valueC) roundD = round(valueD) roundE = round(valueE) # Output rounded values print("Value:".ljust(15), "Rounded:") print(str(valueA).ljust(15), roundA) print(str(valueB).ljust(15), roundB) print(str(valueC).ljust(15), roundC) print(str(valueD).ljust(15), roundD) print(str(valueE).ljust(15), roundE) 6 functionThe That sounds abstract, but is just another way of saying that Here’s a quick example of the # Example: round values down to the next full integerTo explore how the We first import the Next we round those values down. For that we call the The program’s third part outputs the variables with Python’s READ MORE
# Round up to the next integer: Python’s # Some numbers to round valueA = 3.14159265359 valueB = 1845.7409947 valueC = -100.95 valueD = 9.5432 valueE = 34.49953 # Round values to whole numbers roundA = round(valueA) roundB = round(valueB) roundC = round(valueC) roundD = round(valueD) roundE = round(valueE) # Output rounded values print("Value:".ljust(15), "Rounded:") print(str(valueA).ljust(15), roundA) print(str(valueB).ljust(15), roundB) print(str(valueC).ljust(15), roundC) print(str(valueD).ljust(15), roundD) print(str(valueE).ljust(15), roundE) 7 functionThe That’s just a way of saying that Here’s a quick example of Here’s a way to remember the difference between Now the “ceiling” is the higher endpoint of this interval. So Python’s # Example: round Python values up to whole numbersLet’s see how We first import the The next part rounds those values up to a full integer. To make that happen we call the The third code segment has the LEARN MORE
# Round all values in a Python list or arrayOf course there are also situations where we have a bunch of values to round, rather than a single value. There are two main ways to do that: with a list comprehension or # Round Python values with a list comprehensionWhen we have a sequence of floating-point values, one way to round them is with a list comprehension. That requires just a bit of code and runs efficiently. Here’s a mini-program that does just that: First we import the To round those values to whole numbers we make three list comprehensions. The first one executes We generate the values that those functions use with an in-line Those list comprehensions generate new lists. We assign those to the The last part of the program outputs the original list and the three rounded ones. Here’s how that looks: In the above example we kept the original list. If you don’t need to retain those values, you can also overwrite the original list with rounded values. Here’s how a list comprehension does that: # Round all values with Python’s # Some numbers to round valueA = 3.14159265359 valueB = 1845.7409947 valueC = -100.95 valueD = 9.5432 valueE = 34.49953 # Round values to whole numbers roundA = round(valueA) roundB = round(valueB) roundC = round(valueC) roundD = round(valueD) roundE = round(valueE) # Output rounded values print("Value:".ljust(15), "Rounded:") print(str(valueA).ljust(15), roundA) print(str(valueB).ljust(15), roundB) print(str(valueC).ljust(15), roundC) print(str(valueD).ljust(15), roundD) print(str(valueE).ljust(15), roundE) 8 loopOf course we can also round list or array values with a regular Here’s how a Python program rounds values inside a We again first import the Then we make three initially empty lists: To fill those lists we make a Python Inside the loop we call the The program ends with several By the way, you don’t have to make a new list when you round values. If you’re fine with losing the original data, you can also overwrite the existing list. Doing so is easy when you combine a READ MORE
# SummaryPython has three ways to round a floating-point value to a whole number. The The All three functions work in the same way: provide the function with one argument, which is the floating-point value to round. ReferencesLutz, M. (2013). Learning Python (5th Edition). Sebastopol, CA: O’Reilly Media. Python.org (n.d. a). Built-in Functions. Retrieved on November 8, 2019, from https://docs.python.org/3/library/functions.html Python.org (n.d. b). math — Mathematical functions. Retrieved on October 22, 2019, from https://docs.python.org/3.8/library/math.html Published December 20, 2019. # Related Python tutorials
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