Filter rows in pandas with query()

pandas_query.ipynb

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    "# Filter rows in `pandas` with `query()`\n",
    "\n",
    "Cheat sheet: https://twitter.com/prthgo/status/1516036455730229255?s=20&t=pxT30xMIr_L9JNON3EYJDA"
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   "source": [
    "import pandas as pd"
   ]
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       "<div>\n",
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       "  <thead>\n",
       "    <tr style=\"text-align: right;\">\n",
       "      <th></th>\n",
       "      <th>a</th>\n",
       "      <th>b</th>\n",
       "      <th>c</th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th>0</th>\n",
       "      <td>1</td>\n",
       "      <td>2</td>\n",
       "      <td>4</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>1</th>\n",
       "      <td>1</td>\n",
       "      <td>2</td>\n",
       "      <td>1</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2</th>\n",
       "      <td>4</td>\n",
       "      <td>4</td>\n",
       "      <td>1</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
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      "text/plain": [
       "   a  b  c\n",
       "0  1  2  4\n",
       "1  1  2  1\n",
       "2  4  4  1"
      ]
     },
     "execution_count": 2,
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   "source": [
    "df = pd.DataFrame(\n",
    "    [\n",
    "        [1, 2, 4], \n",
    "        [1, 2, 1], \n",
    "        [4, 4, 1]\n",
    "    ],\n",
    "    columns=[\"a\", \"b\", \"c\"]\n",
    ")\n",
    "df"
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   "metadata": {},
   "source": [
    "## Conditions inside the selection brackets"
   ]
  },
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       "    .dataframe thead th {\n",
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       "</style>\n",
       "<table border=\"1\" class=\"dataframe\">\n",
       "  <thead>\n",
       "    <tr style=\"text-align: right;\">\n",
       "      <th></th>\n",
       "      <th>a</th>\n",
       "      <th>b</th>\n",
       "      <th>c</th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th>1</th>\n",
       "      <td>1</td>\n",
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       "   a  b  c\n",
       "1  1  2  1"
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   "source": [
    "df[(df[\"a\"] < 4) & (df[\"c\"] < 4)]"
   ]
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   "metadata": {},
   "source": [
    "## `query()` for Boolean expressions"
   ]
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       "    }\n",
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       "  <thead>\n",
       "    <tr style=\"text-align: right;\">\n",
       "      <th></th>\n",
       "      <th>a</th>\n",
       "      <th>b</th>\n",
       "      <th>c</th>\n",
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       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th>1</th>\n",
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       "      <td>1</td>\n",
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       "   a  b  c\n",
       "1  1  2  1"
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   "source": [
    "df.query(\"a < 4 and c < 4\")"
   ]
  }
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Good to know. Though I do prefer if there's just one way to do something, even if clunky. Does it still work if there's a space in the name?

If the column name "a" was called "a a", the query would look like this:

df.query("`a a` < 4 and c < 4")