Changing node value in XSLT depending on conditions - xslt

Question

I'm new in XSLT and have a problem with converting values.
I have XML node:
<NPD>0</NPD
type in XSD:
<xs:element name="NPD" type="xs:boolean" minOccurs="0"/>
I've created XSLT visualisation using Altova StyleVision but now I have to change in NPD node value "0" to string "No" and value "1" to string "yes".
How can I obtain this effect?
<td colspan="3" style="padding-left:10px; width:1.40in; ">
<xsl:for-each select="$XML">
<xsl:for-each select="wnio:DD">
<xsl:for-each select="wnio:NPD">
<span style="color:#0024c0; ">
<xsl:apply-templates/>
</span>
</xsl:for-each>
</xsl:for-each>
</xsl:for-each>
<span>
<xsl:text>  </xsl:text>
</span>
</td>

Answer 1

Use template rules:
<xsl:template match="wnio:DD[.='0']">No</xsl:template>
<xsl:template match="wnio:DD[.='1']">Yes</xsl:template>

Answer 2

You can use xsl:choose to perform if/switch like statements in XSLT. Here's an example which should work for your scenario:
<xsl:template match="NPD">
<xsl:choose>
<xsl:when test="./text()='0'">
<xsl:text>No</xsl:text>
</xsl:when>
<xsl:when test="./text()='1'">
<xsl:text>Yes</xsl:text>
</xsl:when>
<xsl:otherwise>
<xsl:message terminate="yes">The Yes/No value to be translated did not match expected input</xsl:message>
</xsl:otherwise>
</xsl:choose>
</xsl:template>
See https://www.w3schools.com/xml/xsl_choose.asp for more.
That said, Michael Kay's answer's way better; beautifully elegant & to the point.