Return multiple columns from pandas apply()

👻 Check our latest review to choose the best laptop for Machine Learning engineers and Deep learning tasks!

I have a pandas DataFrame, df_test. It contains a column "size" which represents size in bytes. I"ve calculated KB, MB, and GB using the following code:

df_test = pd.DataFrame([
    {"dir": "/Users/uname1", "size": 994933},
    {"dir": "/Users/uname2", "size": 109338711},
])

df_test["size_kb"] = df_test["size"].astype(int).apply(lambda x: locale.format("%.1f", x / 1024.0, grouping=True) + " KB")
df_test["size_mb"] = df_test["size"].astype(int).apply(lambda x: locale.format("%.1f", x / 1024.0 ** 2, grouping=True) + " MB")
df_test["size_gb"] = df_test["size"].astype(int).apply(lambda x: locale.format("%.1f", x / 1024.0 ** 3, grouping=True) + " GB")

df_test


             dir       size       size_kb   size_mb size_gb
0  /Users/uname1     994933      971.6 KB    0.9 MB  0.0 GB
1  /Users/uname2  109338711  106,776.1 KB  104.3 MB  0.1 GB

[2 rows x 5 columns]

I"ve run this over 120,000 rows and time it takes about 2.97 seconds per column * 3 = ~9 seconds according to %timeit.

Is there anyway I can make this faster? For example, can I instead of returning one column at a time from apply and running it 3 times, can I return all three columns in one pass to insert back into the original dataframe?

The other questions I"ve found all want to take multiple values and return a single value. I want to take a single value and return multiple columns.

👻 Read also: what is the best laptop for engineering students?

We hope this article has helped you to resolve the problem. Apart from Return multiple columns from pandas apply(), check other ast Python module-related topics.

Want to excel in Python? See our review of the best Python online courses 2023. If you are interested in Data Science, check also how to learn programming in R.

By the way, this material is also available in other languages:

• Italiano Return multiple columns from pandas apply()
• Deutsch Return multiple columns from pandas apply()
• Français Return multiple columns from pandas apply()
• Español Return multiple columns from pandas apply()
• Türk Return multiple columns from pandas apply()
• Русский Return multiple columns from pandas apply()
• Português Return multiple columns from pandas apply()
• Polski Return multiple columns from pandas apply()
• Nederlandse Return multiple columns from pandas apply()
• 中文 Return multiple columns from pandas apply()
• 한국어 Return multiple columns from pandas apply()
• 日本語 Return multiple columns from pandas apply()
• हिन्दी Return multiple columns from pandas apply()