How to Use Excel's SIGN Function in Pandas

In Excel, the SIGN function is used to determine the sign of a number. It returns 1 for positive numbers, -1 for negative numbers, and 0 for zero.

This page explains how to replicate Excel's SIGN functionality in Python using pandas.

Implementing the Determine the Sign of a Value function in Pandas#

In Python's pandas library, determining the sign of values can be accomplished in various ways based on specific needs. Here are some common implementations:

Identifying the Sign of Values#

Just like in Excel where you'd use =SIGN(A1) to determine the sign of a value in cell A1, in pandas, you can use the `sign` method.

The following code determines the sign of each value in the 'Column1' and stores the result in a new column 'Sign':

df['Sign'] = df['Column1'].apply(np.sign)

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Creating Indicator Variables#

In some analytical scenarios, you might want to create binary indicator variable based on the sign of values.

For example, in Excel, you might use a formula like =IF(SIGN(A1) = 1, 1, 0) to create an indicator for positive values. To create the same bevahior in pandas, you can use the following code:

# If the number in Column1 is negative, 0 or NaN, label it 0.
# Otherwise, label it 1.
df['Is_Positive'] = (df['Column1'].apply(np.sign) == 1).astype(int)

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Common mistakes when using SIGN in Python#

Implementing the SIGN function in pandas has some potential pitfalls. Here's a common mistake and how to avoid it.

Not Handling NaN Values#

When working with datasets, there may be missing values (`NaN`). It's essential to be aware that the sign function in pandas will return NaN for these values, whereas Excel will return 0 for blank cells.

To implement the same behavior in pandas, you can use the `fillna` method to convert NaN values to 0 before determining the sign.

# Convert NaN values to 0 before determining the sign
df['Column1'].fillna(0, inplace=True)
df['Sign'] = df['Column1'].apply(np.sign)

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Understanding the Determine the Sign of a Value Formula in Excel#

The SIGN function in Excel simply requires one argument, which is the number you want to determine the sign for.

=SIGN(number)

SIGN Excel Syntax

Examples