# Issue

I am trying to **replace all values** in a pandas dataframe column `df.column_A`

**if they fall within the range** of 1 to 10.

However, when I do:

```
df.loc[(1 < df.column_A < 10), "Column_A"] = 1
```

Produces:

```
ValueError: The truth value of a Series is ambiguous. Use a.empty, a.bool(), a.item(), a.any() or a.all()
```

Alternatively, when I do:

```
df.loc[(df.column_A < 10) & (df.column_A > 1), "df.column_A"] = 1
```

I am not getting an error at all, but the values don't get replaced.

What is strange is that when I do:

```
df.loc[(df.column_A < 10) | (df.column_A > 1), "df.column_A"] = 1
```

all values in `df.column_A`

get replaced with `1`

, as I would expect.

This means that the syntax of the line is correct, so the mistake must be due to some factors I don't understand.

What am I doing wrong?

# Solution

It is a simple problem. `.loc`

takes index labels or boolean list/Series. So this will work:

```
df.loc[(df.column_A < 10) & (df.column_A > 1), "column_A"] = 1
```

Note that I removed `df.`

from the column index place.

```
df.loc[(1 < df.column_A < 10), "Column_A"] = 1
```

Will not work because the operation `(1 < df.column_A < 10)`

seems logical, but tries to collapse the whole Series into one value. And since it does not know whether you want an `and`

, `or`

or some other combination, it raises that error.

```
df.loc[(df.column_A < 10) | (df.column_A > 1), "df.column_A"] = 1
```

Should not work either, because you are not referencing the columns correctly. It is funny that you are getting no errors. Perhaps you did something in your program earlier that saves you...

Answered By - Kartik Answer Checked By - David Goodson (PHPFixing Volunteer)

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