擅长:python、mysql、java
<pre><code># Get the index where jan starts
months_index_start = df.columns.get_loc("jan")
# Calculate the total salary for each row according to the months_worked column
df["total_sal"] = df.apply(lambda x : x[months_index_start : months_index_start + x["months_worked"]].sum(), axis = 1)
</code></pre>