This is part of the Semicolon&Sons Code Diary - consisting of lessons learned on the job. You're in the dependencies category.

Last Updated: 2021-05-16

This tip is a simple intuition (that seems near obvious in retrospect) about guessing the argument form in some dependency's API.

I struggled using the Python pandas' `.iloc`

method. My goal was to get the data
for a certain column (`real_prob`

was its title) available on a bunch of rows
with known index locations.

My code was:

```
row_indexes = [899, 1044, 482...]
df.iloc[row_indexes, "real_prob"] = 0.9
```

This failed. The errors didn't help me solve it, but I eventually realized that
`iloc`

expected numerical indexes for *every* dimension. Therefore this would
have worked (assuming `real_prob`

was the 4th column - 3rd with 0-indexing)

```
row_indexes = [899, 1044, 482...]
df.iloc[row_indexes, 3] = 0.9
```

Or I could have calculated it dynamically:

```
df.iloc[row_indexes, df.columns.get_loc("real_prob")] = 0.9
```