Python ValueError：invalid literal for int()，数据类型转换问题求助

Hey there! Let's work through that data type conversion error you're facing. The root issue is simple: your value column contains decimal strings like '86.244', and you can't convert these directly to integers—Python doesn't know how to parse a string with a decimal point into an int without first handling the decimal part.

Solution 1: Convert Columns to Their Correct Target Types #

Instead of trying to convert both columns to integers in one step (or chaining float → int for all columns), specify the exact type each column needs using a dictionary with astype():

# Select the relevant columns and convert each to the appropriate type
df_sub = df_data[['value', 'year']].astype({
    'value': float,  # Keep decimal precision (critical for productivity metrics)
    'year': int      # Year should be an integer for indexing
})

This preserves the meaningful decimal values in value while converting year to a proper integer for sorting and indexing.

Solution 2: If You Need Integer Values for value (Truncate Decimals) #

If you specifically need whole numbers for value (e.g., rounding or truncating decimals), handle the column conversion separately to avoid confusion:

df_sub = df_data[['value', 'year']].copy()
# First convert value to float, then to int (truncates the decimal portion)
df_sub['value'] = df_sub['value'].astype(float).astype(int)
# Convert year directly to integer
df_sub['year'] = df_sub['year'].astype(int)

Note: This will lose the decimal precision from your original data—only use this if you're certain you don't need those decimal values for your analysis.

One Quick Fix for Your Plot #

I noticed your code ends with mp.show instead of mp.show()—you need the parentheses to actually render the plot in Jupyter. Update that line to:

mp.show()

Why Your Original Code Failed #

The error ValueError: invalid literal for int() with base 10: '86.244' occurs because df_data[['value', 'year']].astype(int) tries to convert the decimal string '86.244' directly to an integer. Python can't parse a string with a decimal point as a base-10 integer, hence the failure.

内容的提问来源于stack exchange，提问作者FrenchConnections