04. Understanding Columns.ipynb

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    "# Understanding Columns"
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   "source": [
    "import pandas as pd"
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   "source": [
    "df = pd.read_csv(\"data/imdb_1000.csv\")"
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   "source": [
    "## Selecting columns\n",
    "\n",
    "When you read a CSV, you get a kind of object called a DataFrame, which is made up of rows and columns. You get columns out of a DataFrame the same way you get elements out of a dictionary."
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   "source": [
    "df.columns"
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   "source": [
    "df['star_rating']"
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   "source": [
    "df[['star_rating', 'title']]"
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   "source": [
    "On the inside, the type of a column is ``pd.Series`` and pandas Series are internally numpy arrays. If you add ``.values`` to the end of any Series, you'll get its internal **numpy array**."
   ]
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   "cell_type": "code",
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   "source": [
    "type(df['star_rating'])"
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   "source": [
    "sr = df['star_rating']"
   ]
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   "source": [
    "df.index"
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   "source": [
    "sr.index"
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   "metadata": {},
   "outputs": [],
   "source": [
    "sr.values.mean()"
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  }
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